June 26, 2026

expert reaction to the Met Office issuing amber and red extreme heat warnings

Scientists comment on the extreme amber and red heat warnings issued by the Met Office for the week beginning 22nd June 2026.

Prof Keith Bell, Holder of the ScottishPower Chair in Future Power Systems, University of Strathclyde; and leader of the Energy Infrastructure research theme at the UK Energy Research Centre (UKERC), said:

Air conditioning and meeting demand for electricity in the summer

“According to Energy Dashboard, during the day for much of yesterday (June 25), solar power made up one third of total GB electricity generation, an extraordinary level given the nature of Britain’s power system only a few years ago.  https://www.energydashboard.co.uk/live

“If enough low carbon generation capacity is installed to meet winter peak demand, it should also be enough to meet the summer peak, even with extra air conditioning.  Thus, extra electricity use for cooling shouldn’t be a major threat to decarbonisation and reduction of dependency on fossil fuels.  However, to minimise our use of electricity, we should make as much use as possible of passive cooling methods such as shading and good design of buildings.  Industrial cooling needs to be designed to minimise impacts on scarce water resources.

“Very hot weather conditions might also mean low wind speeds.  In addition, the efficiency of thermal power plant such as nuclear power stations will be lower.  In France this week some nuclear power stations have had to stop running because river water used for cooling has been too hot.  This has increased the price Britain needs to pay for imports of power.

“Overall, this illustrates the need for our National Energy System Operator have a diverse range of sources of electricity to meet demand.  This includes the option of giving consumers financial rewards for changing when they use electricity – such as for EV charging – to the times when demand is easiest to meet.  This has been very effective this week.

Electricity networks in hot weather

“Air conditioning demand is well-correlated with Solar PV output.  However, the solar PV generation and the biggest air conditioning loads aren’t necessarily in the same places.  There is therefore a need for enough network capacity for demand to be met reliably.

“Although electricity demand in the summer is generally lower than in the winter, the summer is when at least some network equipment gets taken out of service for maintenance, depleting network capacity.  Also, equipment gets hotter in hotter weather meaning it can’t carry as much current.  If this isn’t managed carefully by the network owner, equipment could overheat and trip, potentially disconnecting electricity users.  This shows the importance of Britain’s infrastructure being well adapted to climate change.”

Wildfires:

Prof Stefan Doerr, Director Centre for Wildfire Research, Swansea University; and Editor-in-Chief, International Journal of Wildland Fire, said:

Do heatwaves ‘cause’ wildfires or does there always have to be an ignition source?

“Heatwaves do not normally cause fires.  Especially when combined with low air humidity and wind, they can rapidly dry out dead vegetation and also reduce the moisture held in living vegetation.  This makes the landscape more likely to carry a fire when there is an ignition source such as a campfire, BBQ or sparks from machinery or electric equipment.  Theoretically peat can also self-ignite under very specific conditions, however, this is very rare and by far the most common cause of vegetation fires in the UK is accidental or intentional ignition.

Are wildfires more likely during heatwaves – if so do we know why this is?

“Yes (as per above): especially when combined with low air humidity and wind, they can rapidly dry out dead vegetation and also reduce the moisture held in living vegetation.  This makes the landscape more likely to carry a fire fuelled by dead and living vegetation.

“The weather forecast for Friday and Saturday near Glossop predicts falling humidity and increasing wind gusts.  This could further promote the intensity and spread of the fire if it is not contained before.”

Prof James Allan, Professor of Air Pollution Measurement, NCAS (National Centre for Atmospheric Science and University of Manchester, said:

Do heatwaves ‘cause’ wildfires or does there always have to be an ignition source?

“Heatwaves make wildfires more likely, but there always has to be an ignition source.  While fires can be started deliberately through arson, many are often accidental through activities such as barbecues or smoking.  But even without any human activity, it is also possible for them to start naturally, such as through lightning strikes.

Are wildfires more likely during heatwaves – if so do we know why this is?

“Wildfires are more likely during heatwaves, particularly prolonged ones, because the vegetation gets dried out and so is easier to ignite and sustain a fire.  In the case of moorland fires, peat within the soil can burn if the ground is dry enough, and this can be extremely difficult to extinguish once started.  If a warm period in the spring or summer follows a period of rainfall, this can initially cause a lot of plant growth, so if this new growth subsequently dries out during hot weather, there can be more material to burn, also making a fire more intense and likely to sustain itself.”

Dr Thomas Smith, Associate Professor in Environmental Geography, London School of Economics and Political Science (LSE), said:

“For any wildfire, you need fuel (vegetation) available to burn, a source of ignition, and fire-conducive weather.  As far as the weather is concerned, the current heatwave has presented some risk, due to the high temperatures, however the unusually high humidity (40-50% relative humidity) and calm winds (which is why this heatwave has been particularly uncomfortable) has somewhat offset the risk presented by the high temperatures.  Also, we are fairly early in the summer, when most vegetation that might be susceptible to fires (heather, gorse, grasses) contains plenty of moisture due to recent rain and a fairly average spring in terms of precipitation.  These weather and fuel (vegetation) factors should lead to less extreme fire behaviour — slow moving fires with shorter flames — this is why we haven’t had any forecasted ‘extreme’ conditions in this heatwave to date.  The heatwave of July 2022 was very different, with extremely low humidity (<20% relative humidity) and high winds on the hottest day ever recorded (19 July 2022) following a period with little rain so plenty of fuel was available to burn, leading to extreme fire behaviour.

“Nevertheless, fires are still possible in these conditions.  Ignition sources are almost exclusively from human activity — either accidental or intentional — with barbecues, camp fires, electrical equipment, or arson being typical ignition sources in the summer months.  Local weather conditions, particularly in hilly terrain, could focus winds, and vegetation on slopes at an angle facing the sun may also become drier, all helping to drive more extreme fire conditions.  This may well have been the case in the hills around Glossop.”

Health:

Dr Jessica Mee, UKRI Future Leaders Fellow Female Health and Heat Physiology, University of Worcester, said:

“Children are more vulnerable to heat than healthy adults due to factors like higher surface area-to-body mass ratio, less sweating, poor thirst recognition, more likely to engage in physical activity, and less likely to pace themselves.  What constitutes a dangerously high temperatures for children depend on factors like humidity, sun exposure, and exertion levels.  However, prolonged exposure to temperatures above 30°C can increase the risk of heat-related illnesses.

”Altering school schedules during heatwaves can be a sensible precaution.  Starting earlier, reducing outdoor activities, and providing more breaks can help minimise heat exposure.  However, the effectiveness depends on the school’s ability to provide cool, well-ventilated indoor spaces and green well shaded outdoor spaces in the early morning.  Many homes, especially in urban areas, are poorly designed for staying cool.

“Things to think about when it comes to children in heatwaves include: ensuring children stay well-hydrated; encouraging rest in cool, shaded areas; dressing children in light, loose-fitting clothing; and monitoring for signs of heat distress, such as fatigue, dizziness, or nausea.

“Schools must be adequately prepared for heatwaves, as these events will continue to occur.  Currently, many schools are reactive rather than proactive.  They need clear heatwave plans, including provisions for cool spaces, schedule changes, and staff training to ensure children’s safety.

“When discussing heatwave vulnerability, we also need to expand our understanding beyond the young, elderly, and health compromised.  Many other groups face increased risks, including:

• Pregnant women, who experience altered thermoregulation and heat sensitivity;

• Menopausal women, who may struggle with hot flashes and night sweats;

• Caregivers, who face the added burden of keeping others cool and hydrated;

• Outdoor workers and those with physically demanding jobs;

• People in occupations requiring heavy cognitive processing, as heat can impair       mental function;

• Education professionals, who often work in older, poorly ventilated buildings and       face the challenge of keeping students safe and comfortable during heatwaves;

• Healthcare workers, who must manage the added burden of increased hospital       admissions, heat-related illnesses, and ensure the comfort and safety of patients in clinical settings;

• Gig workers, such as delivery drivers and couriers, who often lack access to cool rest       areas, hydration, and shade during their shifts;

• Individuals in poorly ventilated or temperature-controlled housing.

“During heatwaves, education and healthcare professionals often face additional strain.  Teachers may need to manage overheated classrooms, adjust lesson plans, and ensure students stay hydrated.  Healthcare workers may see an influx of heat-related illnesses, manage patients’ comfort in warm hospital wards, and face increased stress and fatigue.  To truly protect public health, we must recognise and support the diverse range of people who may struggle during heatwaves.  This means tailoring guidance, interventions, and resources to meet the unique needs of these various groups.  By broadening our definition of ‘vulnerable populations,’ we can build a more inclusive and effective approach to heatwave resilience.”

Dr Laurence Wainwright, Senior Departmental Lecturer – School of Geography and the Environment, and Senior Researcher – Department of Psychiatry, University of Oxford, said:

“Children are significantly more vulnerable to the effects of extreme heat than adults. There are three primary intersecting reasons for this.  First, the biological systems responsible for thermoregulation, primarily governed by the hypothalamus in the brain, are not fully developed in children (especially those under 5), making them less capable of cooling down.  Furthermore, the small physical size of children means they poses a substantially greater body surface area-to-mass ratio than adults, resulting in an accelerated rate of heat transfer into a child’s body.  Finally, children exhibit much higher rates of metabolic heat production (in relation to their size) compared to adults.  These three factors combined cause a child’s core temperature to rise significantly faster, and stay high, compared to that of an adult put under the same temperatures.

“The current heatwave has utterly exposed the unpreparedness of the UK to deal with high temperatures.  Perhaps nowhere more has this been felt more than in our schools.  It is a travesty that any school in the UK should have to close entirely, or significantly reduce operating hours, because of heat.  The situation we find ourselves in now is highly predictable and could have been prevented with proper action and infrastructure investment from the Government.  Less than 5% of school classrooms across Britain have air conditioning.  While aircon does of course contribute to carbon emissions – paradoxically making the problem of climate change worse – it is by far the quickest and most effective way to make classrooms suitable for learning, and safe for children, during heatwaves.  Installation of aircon in at least 25% of existing school classrooms should have already happened and is an absolute necessity for a future where heatwaves like this will be common.  For new builds, the government must embrace sustainable cooling practices in its designs.

“The Department of Education has over the years taken the stance that in general, schools should try to remain open during periods of extreme heat, on the basis that heat can usually be managed through operational adjustments (e.g. more frequent breaks, uniform policy lenience, avoidance of physically strenuous sporting activities).  While this may work when temperatures sit around 28c, by 36c (as we saw today), the whole learning experience quickly starts to deteriorate, and eventually becomes untenable.  Multiple studies have shown that school test results go down when the indoor temperature gets above 28c – up to a 15% reduction in results versus students sitting in a room of 18c.  Child behaviour and learning ability is significantly impacted by heat.  They find it harder to exercise higher order cognitive functions (such as critical thinking and being able to apply newly-learnt concepts in practice).  Impulse control is impaired and children are more likely to act out and misbehave.  They find it much harder to focus and concentrate.  Turning up to school having had a bad night’s sleep from high indoor temperatures at home makes the problem even worse.

“Principals and teachers must be realistic about what is and isn’t possible on a hot day and lower expectations.  Perhaps scheduling the most cognitively intense classes early in the morning when it is comparatively cooler rather than holding an advance mathematics class and trying to teach algebra for the first time when it is 33c inside.  Shortening the school day by an hour or so makes sense.  Frequent water breaks are essential, as is having a shared cooling space in the school grounds that students can access intermittently (such as a gym with air conditioning or a modern building with a cool underground area).”

Dr Malcolm Mistry, Assistant Professor in Climate and Geo-Spatial Modelling, The Environment & Health Modelling (EHM) Lab, London School of Hygiene & Tropical Medicine (LSHTM), said:

“Whether altering the school day or sending children home from school is better for children in this heat depends on the state of the school and the circumstances at home – which won’t be the same for all children.  It is right that physical activity in schools should be suspended during this heatwave.  A typical school day in the UK is between 08.30-15.30h.  If altering a school day implies an earlier start and end time, the risk might be exposing more children to early afternoon heat, e.g., at noon.  The challenge here is to ensure that those children who travel on their own are not going to remain exposed to outdoor heat -especially direct sunlight.  This could be a risk if they spend more time in outdoor spaces such as parks.  Not all children have the luxury of living in accommodations that are able to maintain the thermal comfort better than what their schools can maintain during daytime.  There needs to a scientific discussion and effective policy guidelines in place advising schools rather than some arbitrary decisions by individual schools.”

Dr Raquel Nunes, Associate Professor in Health and Environment, University of Warwick; and UKRI Natural Hazards and Resilience Policy Fellow, said:

“The detail that matters most in this warning is not the daytime peak approaching 38°C, it is the nights.  The Met Office is forecasting consecutive Tropical Nights, when temperatures stay above 20°C, especially in towns and cities.  Sustained heat with no overnight relief is what does the damage, because the body never gets the chance to recover.  That cumulative strain, made worse by high humidity, is what tips older and frailer people from coping into serious illness.

“An amber warning escalating to red is the system recognising danger in advance, which is what it is for.  But a warning is the first link in a chain, not protection in itself.  My work on heat and older populations starts from a simple idea: vulnerability is not a fixed property of being old or unwell.  It is shaped by the assets a person can draw on, such as a cool space, someone checking on them, the means to act on advice.  Resilience is the capacity to hold onto those assets when conditions turn extreme, and that capacity is unevenly distributed.

“This is also a test of where people are cared for.  In England, heat-associated deaths concentrate in care homes, hospitals and people’s own homes, and last summer care homes saw the largest rise of all.  So part of the answer may not be behavioural but structural: buildings that stay cool overnight, and care settings resourced to protect people through a sustained heat episode.

“The real measure of a warning system is not how many people hear it.  It is whether protection reaches the people least able to arrange it for themselves, and the settings responsible for those who cannot.”

Dr Eunice Lo, Senior Research Fellow in Climate Change and Health at the University of Bristol Cabot Institute for the Environment, said:

“We must adapt to hot weather now, as it is going to increase in intensity and frequency due to climate change.  According to Met Office simulations designed to study unprecedented heat, even 45 degrees heat is plausible under current climate.  By chance, this hasn’t occurred yet and is not forecast for this week, but it could happen in the near future.

“Having just co-led the ‘Heat risk to people’ section of the latest UK Climate Change Risk Assessment (CCRA4), we already have lots of evidence for the Very High risk extreme heat poses to UK health, especially on heat-mortality, both now and through to the end of this century.  People often recall the heatwave in 1976, but a similar 2-week event occurring in today’s climate would be about 3 degrees Celsius hotter.  Without adaptation, that would roughly mean a doubling of heat-mortality risk.  This risk can be reduced with adequate adaptation; therefore we must look after ourselves and others right now.”

Dr Ruby Lieber, Senior Research Associate at the University of Bristol Cabot Institute for the Environment, said:

“Heat is one the biggest climate-related health threats facing the UK and will continue to threaten thousands of lives every year unless widespread adaptation and mitigation is implemented.

“This heatwave is particularly threatening because of the higher humidity which makes it harder for the body to cool down as well as the lack of relief overnight as nighttime temperatures are expected to stay high (above 20 degrees).

“An attribution study is required to understand the exact influence of climate change on this specific heatwave and its impacts however we know that climate change is making heatwaves like this more common and more severe.”

Prof Claire Steves, Professor of Ageing and Health and lead of the Centre for Ageing Resilience in a Changing Environment (CARICE), King’s College London:

“Older people are much more at risk from heatwaves than younger people.  If you’re an older person, there are a few things you can do to help keep yourself safe.

“If you’re older, you may not have the same thirst that a younger person has when it gets hot, so make sure you drink plenty of water.  If you’re looking after somebody who’s older, remember they may not have the same urge to drink that you have, so keep prompting them to drink.

“Older people don’t sweat as much as younger people.  We can combat this by using devices like water sprays to help keep cool, or even just a damp cloth on the skin to help remove heat.  Using a fan can also help and, if you have access to it, use air conditioning.

“Make sure you close the windows and curtains during a heat wave, especially on the sunny side of the house, to keep the heat out.

“Having a good sleep in a cool bedroom is also important for reducing the risk to older people during heatwaves.  You can do this by opening the windows when it gets cooler at night.  Also drinking a cold drink just before bed and making sure your bed clothes are not too heavy will help.”

Dr Matt Maley, Senior Lecturer in Environmental Physiology and Ergonomics, Loughborough University, said:

How do human bodies cope with heat?

“We regulate our body temperature within a narrow range, but when the air temperature is warmer than our skin temperature (often 33°C), as it is during this heat wave, we rely on evaporation of sweat to keep our body temperature within safe limits.

Are there certain people who are more vulnerable to heat than others?

“Those who have compromised skin blood flow and sweating responses will have difficulty regulating their body temperature.  Groups such as those with cardiovascular disease, diabetes, and those with spinal cord injuries will be included in this. Older adults often have a diminished sweating response, too.  These individuals will need to take extra care during spells of hot weather.  Simple advice will go a long way in reducing instances of heat exhaustion: keep hydrated, shaded where possible, and light, loose clothing will aid ventilation.”

Dr Neil Maxwell, Reader of Applied Environmental Physiology, Environmental Extremes Lab, University of Brighton, said:

“Heatwaves are no longer rare events.  They’re becoming a regular part of British summers, which means knowing how to cope with extreme heat is becoming an increasingly important life skill.  This level of heat can affect anyone, not just traditionally vulnerable groups.  High temperatures, strong sunshine and warm nights place additional strain on the body, particularly when people continue with their normal routines.

“The good news is that simple actions can make a significant difference.  Stay hydrated, keep your home cool, avoid strenuous activity during the hottest parts of the day, seek shade where possible and check in on vulnerable family members and neighbours.

“One of the biggest mistakes people make is trying to carry on as normal.  During periods of extreme heat we need to adapt our expectations and behaviours.  Whether you’re exercising, travelling or working outdoors, planning ahead and slowing down can make a substantial difference.  Prevention is always easier than recovery.  As our climate continues to warm, these are skills that will become increasingly important for all of us.”

Dr Alan Dangour, Director of Climate & Health, Wellcome, said:

“As the UK gets a rare red heat health warning, this is not just another heatwave – it’s a growing health threat fuelled by climate change.  And the NHS is not yet prepared for this new reality.

“Vulnerable people like pregnant women are already facing higher risks, including premature birth, during heatwaves.  Simple, practical measures – like keeping maternity wards safely cool and ensuring midwives have clear guidance – could make an immediate difference.

“The health impacts of climate change are already here, and we have an opportunity and responsibility to better protect those most at risk.”

Dr Laurence Wainwright, Senior Departmental Lecturer – School of Geography and the Environment, and Senior Researcher – Department of Psychiatry, University of Oxford, said:

“The health implications of heatwaves can be significant – especially for certain vulnerable groups including outdoor workers, young children, elderly, those taking certain medications, and those with a mental health condition.

“Humans are capable of living in a wide range of climatic extremes, from -30c right up to 50c.  But our bodies need time to adjust.  We are designed to cope with what we are used to, just as the infrastructure of the UK is designed primarily around cool weather rather than heat.  While we can acclimatize, it takes time – many weeks in fact.  When a 35c day – historically very rare in this country – suddenly appears, this is a shock to the system.  Our bodies – especially our brain and heart – struggle, simply because they are not used to it and have to devote most of their energy and effort to stay cool.  As such, other body capabilities (especially cognitive function), suffer.  Given enough time, the body is smart enough to be able to make physical adaptations to cope with the heat.  But it takes time.  In very hot climates, the body adapts by doing things like increasing the plasma volume and sweat rates, while lowering the salt concentration of sweat.  This allows the cardiovascular system to handle heat stress with less strain. Because UK heatwaves are usually brief and intermittent, the population rarely has time to acclimatize to it physically.

“But even when the body eventually adjusts to the heat, this is not enough in the UK to cope effectively.  The country is simply not built or designed to deal with hot days – everything from our NHS and homes and offices to our shopping malls and train lines – is not meant for temperatures above 30c; mainly because these days were so rare in the past.

“The 16% of the UK population with a mental health condition are significantly affected by heatwaves.  Existing symptoms can worsen, new symptoms can emerge, medication side effects can be exacerbated, suicide rates go up, and hospital admissions for mental health reasons increase by 10%.

“Sleep is greatly impacted during heatwaves.  When we have ‘tropical nights’ as we will this week – where overnight temperatures don’t fall below 20c (which in a UK home could mean an indoor temperature as high as 28c), a good night’s sleep is all but impossible for most.  The implications of this are significant.  Less sleep and broken sleep are associated with a drop in work performance and productivity, an increase in accidents, lower school test scores (a 15% drop in a room of students with a temperature of 18c vs 28c), a decline in mental health, worsened cognitive function, and an increase in impulsive behaviours.”

Dr Heather Massey, Associate Professor in Extreme Environments and Physiology, Extreme Environments Laboratory (EEL), University of Portsmouth, said:

How do human bodies cope with heat?

“The human body copes with heat through a process called thermoregulation, which maintains a stable deep body temperature at around 36.5 to 37 °C.  When deep body temperature raises above this blood vessels near the skin widen (vasodilate) to increase heat loss and we sweat, the sweat evaporates from the skin and removes heat.  In addition, people naturally adjust their behaviour by seeking shade, reducing activity, and drinking fluids.  However, these mechanisms become less effective when temperatures are very high or when humidity is elevated, which can prevent sweat from evaporating and increase the risk of heat-related illness.

Are there any specifics related to this forecast heatwave?

“This forecast heatwave is expected to involve several consecutive days of unusually high temperatures, typically exceeding 30 °C in some areas, which is significantly above average for the UK.  A key feature of the event is likely to be elevated night-time temperatures, sometimes remaining above 20 °C, which can prevent the body from cooling down and recovering.  Humidity may also play an important role, as higher moisture levels in the air reduce the effectiveness of sweating that would cool the body.

“People can stay cooler during hot weather by limiting exposure to the hottest parts of the day, typically between late morning and early evening, and by seeking shade or air-conditioned environments whenever possible.  Keeping indoor spaces cool by closing curtains or blinds during the day and opening windows at night can help reduce heat buildup.  Wearing loose, light-coloured clothing made from breathable fabrics such as cotton can improve heat loss.  Taking cool showers or baths, using damp cloths on the skin, spraying the body with water and staying in front of a fan or placing the hands and or feet in a basin of cold water can also help lower body temperature.  It is important to drink fluids regularly throughout the day, even if not feeling thirsty, to replace water lost through sweating.

Are there certain people who are more vulnerable to heat than others?

“Certain groups of people are more vulnerable to heat due to physiological, medical, or environmental factors.  Older adults and young children are at greater risk because they may be reliant on others to adjust their environment, keep them cool and hydrated.  Individuals with pre-existing health conditions, such as cardiovascular disease or conditions that limit blood flow to the surface of the skin or sweat loss, are also more susceptible to heat stress, as are those taking medications that affect hydration or sweating.  In addition, people who are exposed to heat for longer periods, such as outdoor workers, athletes, or those living in poorly ventilated housing, face a higher risk.

Weather / climate

Prof Hayley Fowler FRS FRMetS, Professor of Climate Change Impacts, and Royal Society Faraday Discovery Fellow, Director of Centre for Climate and Environmental Resilience, Newcastle University, said:

“The evolving heatwave in the southern to central UK is forecast to produce unprecedented temperatures for June and is predicted to break the June temperature record set 50 years ago during the record summer of 1976.  Heatwaves are becoming more frequent, longer and hotter with climate change, as a direct result of the fossil fuels we are releasing as a society.  This particular heatwave has almost exactly the same atmospheric circulation set up as in July 2022 which produced record-shattering temperatures over 40 degrees in the UK.  The same sort of temperatures are forecast during this event, in June.  We can expect to have to cope with more and more of these types of events in the years to come.  Our current climate is the least extreme we will live in in our lifetimes, and certainly until we reach Net Zero, and we need to adapt urgently to live and work in these extreme temperatures.”

Prof John Marsham, Professor of Atmospheric Science, University of Leeds, said:

“An amber alert has been issued as a high pressure system and air from continental Europe is expected to bring persistent hot and humid conditions to the southern UK, with temperatures peaking through Wednesday and Thursday.  This heatwave is coming straight after a new record UK maximum temperature for May was set barely a month ago, and we may now see a new record temperature for June.  We should all take appropriate action, including checking on those most vulnerable.  Such heat extremes are of course made far more likely by climate change – even 45 degrees Celsius may now be possible in a UK summer.  Beyond this event, it’s increasingly vital that people understand the global picture, as extreme weather across the world affects the UK, for example by pushing up UK food prices, which together with the cost of fossil fuels is driving the ongoing cost of living crisis.  This will get worse and worse until we have phased out fossil fuels to reach net-zero.  The good news is net-zero is now the cheapest option for the UK, now costing less than just one fossil fuel crisis, let alone two.”

Dr Mireia Ginesta, Research Associate in Climate Damages Analysis at the Oxford Smith School of Enterprise and the Environment, University of Oxford, said:

“This heatwave is exceptionally intense for June.  Temperatures could reach 37–38°C across parts of southern England this week, with a strong possibility that June temperature records will be broken.  The current June record is 35.6°C, set in Southampton in 1976.

“The weather pattern driving this event is not unusual in itself.  A persistent area of high pressure over Europe is causing air to sink and warm as it descends.  At the same time, the high pressure suppresses cloud formation, allowing strong sunshine to heat the ground and push temperatures even higher.

“What is unusual is the intensity of the heat.  Climate change does not create the high-pressure system, but it raises the background temperature on which weather systems operate.  In a cooler climate, this heatwave would have been less intense.  Human-induced warming is making extreme heat events hotter, more frequent, and more likely to break records.

“Heatwaves like this can have serious consequences.  They increase the risk of heat-related illness and death, particularly among vulnerable groups.  They can also lead to significant stress on agriculture, especially when extreme heat occurs earlier than expected in the season, and can disrupt transport, energy, and other critical infrastructure.”

Prof Lizzie Kendon, Professor of Climate Science at the University of Bristol and Head of Climate Projections at the UK Met Office, said:

“This week temperatures are going to smash the all-time UK temperature record for June.  We expect increasing temperatures and the breaking of temperature records due to climate change, and indeed we are already seeing this in the observational record for the UK.  What is so extraordinary, however, is the margin by which the record will be broken.”

Prof Friederike Otto, Professor of Climate Science, Imperial College London said:

“Our first 40°C day was supposed to be a wake-up call, but clearly someone hit snooze.  Hitting 40°C again – and in June this time – would be incredibly alarming.

“There’s a sad inevitability to all of this, with scientists like me trotting out the same quotes year after year.  Yes it’s climate change, yes it’s us, no it’s not El Niño.  Simply put, we remain on a one-way trip towards a more dangerous future, and it’s time we hit the brakes.

“Right now, children are struggling to finish their exams in sweltering classrooms and the elderly are enduring dangerously hot homes and care facilities with little relief.  This heat is not an inconvenience, it is a growing public health threat.  Every heatwave puts lives at risk, and it’s long past time we treated it with the urgency it demands.”

Prof Dann Mitchell, Professor of Climate Science, University of Bristol, said:

“We often see hundreds of death during a heatwave, from drownings on the day, to heart, respiratory, and neurological problems shortly after, to longer term renal and mental health problems in the weeks that follow.  Everyone responds to heat in different ways, with vulnerable groups such as the elderly, babies, and people with certain health conditions being particularly affected.  Anything that changes the way our body’s thermoregulation works can be problematic in a heatwave.  That could be the type of medication people are on, the way they sweat, the housing they sleep in, or how their brain tells them they are thirsty.

“Having just led the UK Climate Change Risks Assessment report on health, this illustrates why we concluded that heat was the biggest risk to health from climate change in the UK.”

Dr Linda Speight, Lecturer in Physical Geography, University of Oxford, said:

“Back in 2022 when temperatures were forecasted to reach 40 °C for the first time and the Met Office issued its first ever Red Heat Warning many people underestimated the risks, with some media coverage dismissing concerns and encouraging people to head to the beach.  The next day, people were shocked as roads melted, wildfires raged close to urban areas, and the heatwave led to nearly 3000 excess deaths in England.

“This time it’s not just the heat that’s a concern.  High humidity levels will make conditions feel even more oppressive for everyone.  We must take the warnings and advice of experts seriously.  Temperatures like the ones forecast this week are dangerous and are going to be an increasingly frequent feature of UK summers from now on.  Taking sensible precautions and changing plans for the week now, will save lives by Thursday.

“The definition of a heatwave varies based on where you are in the UK, as people in the south are considered to be more accustomed to consecutive days of hot weather than those further north.  The forecast for this week is 10 °C degrees above the heatwave threshold in many areas, highlighting the severity of potential impacts and the need to take the warnings seriously.”

Prof Bill McGuire, Professor Emeritus of Geophysical & Climate Hazards, UCL, said:

“The UK temperature broke the 40C barrier in July 2022, so it should come as no surprise that – after another four years of global heating – here we are again.  In the current climate, UK summer temperatures of 43C+ are possible, as are heatwaves lasting for multiple days with temperatures at or close to 40C.  This has massive implications for health, energy infrastructure, and transport, which are simply not built for these conditions.  As 40+ temperatures become ever more common, expect many thousands sleeping in the streets as poorly insulated homes become uninhabitable heattraps, widespread power cuts as power cables sag and break, transport chaos as rails, overhead wires and signalling fail, and A & E departments overwhelmed by the old, very young, and vulnerable suffering from overheating.”

Prof Richard Allan, Professor of Climate Science, Department of Meteorology, University of Reading, said:

“A heatwave in June is par for the course but temperatures nudging toward 40 degrees Celsius were unprecedented for the UK up until 2022.  Whilst May brought record dry heat, this week will see a more muggy heatwave that makes it difficult to stay cool and critical for those with underlying health conditions.

“It is blindingly obvious that heatwaves will increase in severity as rising greenhouse gases stifle the planet’s ability to lose heat to space.  A warmer atmosphere’s greater thirst for water also means more rapidly onsetting droughts but also the intensification of extreme rainfall and associated flooding as excess water drained from the soil and oceans is channelled into storms that can often be sparked off by summer heat.

“The reality of global warming talked about when I was young in the 1980s is now playing out, yet the solution to avoid further dangerous climate change remains unchanged – upgrade our industry, transport and agriculture to vanquish greenhouse gas emissions across all sectors of society.”

Prof Liz Bentley, Chief Executive, Royal Meteorological Society, said:

“The coming week will bring an unprecedented heatwave with temperatures likely to reach 38-39°C.  The current June record is 35.6°C.

“This will lead to two consecutive months, May and June, in which the UK temperature records have been annihilated by well over 2°C.

“The weather pattern driving this heatwave is due to a high pressure system where the air aloft descends and is compressed leading to significant warming.  This is similar to the weather pattern that led to the late May heatwave.

“However one of the overriding reasons we are experiencing more frequent and intense heatwaves is because our climate has changed due to the fossil fuel emissions leading to more dangerous extremes of heat.”

Dr Akshay Deoras, Senior Research Scientist, National Centre for Atmospheric Science & Department of Meteorology, University of Reading, said:

“This is not just a heatwave, it is a heat-dome driven furnace that will grip most of southern UK and push temperatures into truly exceptional territory.

“We are looking at an intense and record-breaking spell of heat with widespread impacts on public health, infrastructure and essential services.  Unlike the heatwaves of May 2026 and July 2022, elevated humidity levels are expected to make conditions feel even more oppressive and dangerous by severely reducing the body’s ability to cool itself through sweating.

“Long-standing June temperature records are set to be shattered by 25 June, potentially by a significant margin, and with temperatures edging dangerously close to levels previously thought almost unimaginable in the UK.

“The driving force behind this event is a heat dome, which is a vast area of high pressure parked over the UK and western Europe.  Think of it as a giant atmospheric lid, suppressing cloud formation and allowing relentless sunshine to bake the ground day after day.  At the same time, air sinking beneath the high pressure compresses and warms, much like air heating up inside a bicycle pump when it is squeezed.

“Human-driven climate change has provided the springboard for this event, loading the atmosphere with extra heat and making extreme temperatures far more intense than they would have been in the past.

“Adding to the concern is the likelihood of widespread tropical nights, where temperatures remain above 20°C after dark.  This prevents homes and buildings from cooling down, leaving many people struggling to sleep and reducing the body’s ability to recover from the daytime heat.”

Dr Chloe Brimicombe, Climate Scientist and Heatwave Researcher, University of Oxford, said:

“This period of extreme heat is forecasted to be the first heatwave of the summer in the UK and Central Europe and countries like Algeria in Northern Africa.

“Heatwaves are becoming more likely with climate change.  It is possible that for a second month in a row record temperatures could be broken – which is quite alarming.  The UK record dates back to the infamous 1976.

“The UK infrastructure is not prepared for heat, but there are lots of solutions to build resilience.  This includes prioritising cooling from heat pumps for the most vulnerable such as care home, hospital, and educational settings.  Designing heat safe policies with organisations and employees.  And understanding how heat increases and planning for that increase in water consumption.  A transition to net zero is necessary to stop summers becoming even hotter.”

Infrastructure / engineering

Mark Apsey MBE CEng FIChemE, Honorary Professor of Engineering, University of Exeter; and Past President, IChemE, said:

“The UK’s built environment was designed to retain heat in winter, not reject it in summer.  That is the core engineering problem this heatwave exposes. Our homes suffer high solar heat gain through glazing, with little external shading to prevent it, limited ability to ventilate and purge heat safely overnight, and almost no mechanical cooling to remove the heat that builds up.  UK homes are also among the most poorly insulated in Western Europe, which drives our winter energy problem, but in summer the dominant issue is unmanaged solar gain in buildings that have no means to cool themselves.

“This event is more demanding than the daytime peak alone suggests.  The risk is driven by sustained heat, high humidity and overnight temperatures that stay high.  Buildings shed heat at night by losing it to cooler outside air.  When nights stay above 20°C, as forecast here, that overnight cooling largely stops, so homes settle into a hot daily cycle with little recovery between days, rather than returning to a safe baseline each night.  Combined with high daytime solar gain through unshaded glazing, indoor temperatures can stabilise at a level that is dangerous to vulnerable people, and the human body gets no overnight relief.  That is why night-time temperatures and duration matter as much as the headline figure, and it is where our housing stock is most exposed.

“The scale of the exposure is well established. Analysis for the Climate Change Committee found that around 90% of existing UK homes are at risk of overheating under a 2°C warming scenario.  Yet the CCC has also been clear that national efforts to combat urban overheating remain weak and poorly monitored, with no coherent cross-government plan to tackle heat in our buildings and cities.  We are, in effect, exposed to a risk we have measured but not acted on.

“The solutions are well understood and largely passive: external shading to stop solar gain at source, secure night ventilation, reflective surfaces, urban greening, and heat pumps specified to cool as well as heat.  None of this depends on future technology.  It depends on treating heat resilience as a delivery priority now, not a problem for later, and on retrofitting our existing stock for a climate that is both hot and cold rather than cold alone.

“There is also a system constraint we cannot ignore.  Active cooling and heat pumps both increase demand for electricity, and connecting and serving that demand is too often slow or constrained by network capacity.  Resilience to heat therefore depends not only on better buildings but on a smarter, more flexible grid.  As a member of the working group for the Royal Academy of Engineering’s National Engineering Policy Centre report Smart Systems for Clean Power, I would highlight that faster, better digitalisation of the energy system is critical to integrating new demand and flexibility, keeping the system reliable and costs down as we electrify.

“From experience delivering retrofit and energy infrastructure across public sector estates, the barrier is rarely the engineering.  It is pace, funding routes and the absence of a coherent plan to adapt existing buildings at scale.  Each heatwave that passes without that plan is a missed opportunity to prepare for the next, which the evidence tells us will be hotter and more frequent.”

Dr Steve Denton FREng FICE FIStructE, Royal Academy of Engineering Vice President and Chair of the NEPC Working Group on Ageing Infrastructure and Managing Director for Civils at WSP, said:

“The current heatwaves and storms are a timely reminder that much of our infrastructure is already under strain, and extreme weather is accelerating that pressure.  As our recent Ageing Infrastructure report shows (https://nepc.raeng.org.uk/reviving-ageing-infrastructure), systems designed for past conditions are being pushed beyond their limits.

“Extreme heat can put additional stress on power and water systems and speed up the deterioration and risk of failure of essential infrastructure like railways and bridges.

“Building resilience now, through better maintenance, smarter design and long-term investment is essential to ensure our infrastructure can continue to cope with growing demand and vital services can operate reliably in a changing climate.”

Prof Jesus Lizana MSc PhD CEng FCIBSE MASHRAE, Associate Professor in the Department of Engineering Science, ZERO Institute, University of Oxford, said:

The climate change impact, now and longer term

“Climate change is increasing heat exposure and cooling needs globally, with extreme heat events occurring more frequently, lasting longer, and affecting larger geographical areas.  Our recent findings, published in Nature Sustainability (https:\www.nature.com\articles\s41893-025-01754-y), show that the Central African Republic, Nigeria, South Sudan, Laos, and Brazil will experience the most significant increases in dangerously hot temperatures if the world reaches 2.0°C of global warming above pre-industrial levels.

“The UK is particularly vulnerable to extreme heat because our buildings, infrastructure and cities were designed for a cool climate, not for prolonged periods of high temperatures.  That means even temperatures that might be considered normal in southern Europe can have significant impacts here.  Heatwave thresholds in the UK are as low as 25–28°C, compared with 30–40°C in parts of the Mediterranean countries.  The challenge lies not only in increasing heat exposure but also in the vulnerability of our infrastructure to heat.  Countries that have lived with heat for decades have designed their buildings, cities and public services to cope with it, whereas the UK is still adapting to this new reality.

“Our recent study published in Nature Sustainability (https://www.nature.com/articles/s41893-025-01754-y) showed how countries with colder climates will see a much larger relative change in uncomfortably hot days, more than doubling in some cases.  Compared with the 2006–2016 period, when the global mean temperature increase reached 1°C over pre-industrial levels, our study finds that warming to 2 °C would lead to a doubling of heat exposure (100% increase) in Austria and Canada, 150% in the UK, Sweden, Finland, 200% in Norway, and a 230% increase in Ireland.  Given that the built environment and infrastructure in these countries are predominantly designed for cold conditions (e.g. dwellings that maximise solar gains and minimise ventilation), even a moderate increase in temperature is likely to have disproportionately severe impacts compared with regions that have greater resources, adaptive capacity, and embodied capital to manage heat.

“A key finding from our recent climate research is that, when considering the total projected increase in heat exposure between 1.0ºC and 2.0°C of global warming above pre-industrial levels, most countries will experience the largest increase in heat exposure during the current decade, as global temperatures rise from 1.0°C to 1.5°C (reaching up to 65% of projected changes).  This underscores the urgent need to accelerate adaptation efforts.  We are already behind.

Impact on infrastructure

“Extreme heat affects multiple infrastructure systems that were not originally designed to withstand such conditions.  Buildings can experience severe overheating, leading to occupant discomfort, health risks, and increased cooling demand.  This can place additional pressure on electricity networks, particularly during peak periods.

“In urban areas, the urban heat island effect can further amplify temperatures.  Our recent studies have found that night-time temperatures in London can be up to 6°C higher than those in the surrounding rural areas.  This creates additional stress on buildings, transport networks, and public services.

Recommendations for adaptation to heat

“In buildings, we should prioritise passive measures before mechanical cooling to be more resilient.  First, external solar shading should be used to minimise solar heat gains.  Second, better ventilation, particularly during cooler night-time periods, can dissipate accumulated heat from indoor spaces and the building fabric.  Third, increased air movement through fans can significantly improve thermal comfort, extending the comfortable temperature range from 21–26°C to 25–29°C, depending on environmental and occupant conditions.  More details in a recent post we published in The Conversation (https://theconversation.com/how-to-make-homes-cooler-without-cranking-up-the-air-conditioning-207243).

“For vulnerable populations, particularly during extreme heat events, air conditioning can provide a quick and cost-effective means of maintaining safe indoor temperatures and mitigating heat-related health risks.  Passive cooling and climate adaptation require time and planning.  When urgently needed, air conditioning can provide an effective solution.”

Prof Sukumār Natarājan, Centre Director for the Centre for Regenerative Design & Engineering for a Net Positive World (RENEW), University of Bath, said:

How do buildings and transport networks cope with heat?

“We know that our transport infrastructure is not designed for extreme heat – train tracks expand and it becomes unsafe for rail operators.  We need to learn from locations in the world that frequently experience similar conditions on how to better design our rail infrastructure – the frequency and severity of heatwaves is simply going to be increasing and infrastructure designed for 20^th century conditions will not be reliable in the 2080s, when the worst effects of climate change will be visible.

“Our buildings have historically not been designed for such extremes.

“High night-time temperatures predicted for this heatwave will mean warm “tropical” nights.  In poorly designed buildings with large windows and no protective shading, the latter being virtually absent in most British homes, the heat gained during the day cannot be easily lost to cool air at night.  In some areas, it might be difficult to open windows due to security or local pollution, making it even harder to cope.

Are there any specifics related to this forecast heatwave e.g. temperatures reached, nighttime temperatures, humidity, number of days of heat that present engineering challenges?

“Buildings that are poorly designed will overheat and this poses several engineering challenges

“In the future, we need to produce reliable descriptions of such heatwaves so that designers can pre-test their buildings before they are built or before they are changed so that mitigatory action can be taken.  A key problem is that weather can be highly local – the temperature at my home in Bath is always lower than that here at the university – the two being only about 5 miles apart.  For this reason, Bath has led the world through our highly-local descriptions of extreme weather, precisely of the sort we are about to experience for every 5 km × 5 km land parcel of the UK, and every 25 km × 25 km for India.

“Developing the skills and knowledge to design out the worst effects of heatwaves is also a key engineering challenge.  This is partly because of our fascination with glass in buildings as a society.  We need to understand that a lot of glass does not just create conditions similar to a solar-cooker indoors, but is also very thermally poor in the winters.  The natural response is to simply add more heating or cooling, which in turn increases our carbon emissions and is obviously not sustainable.  The only answer is better and more weather-aware design.

“Finally, we need to better understand the constraints.  In some locations such as inner cities, risk of crime or other factors such as air pollution or noise will mean ventilation can be highly restricted.  Extra care needs to be taken in such cases, perhaps provisioning for mechanical ventilation opportunities, ideally with heat recovery, so that building occupants can safely ventilate their homes.  Many small and noiseless devises are now available which can also be safely retrofitted to existing buildings, which are a major part of our stock.”

Dr Sotirios Argyroudis, Reader in Infrastructure Engineering, Brunel University of London, who recently advised the National Resilience Committee on infrastructure resilience and cascading climate risk, said:

“Transport infrastructure can usually cope with short heat spikes, but prolonged high temperatures cause cumulative deterioration.  Rail tracks can buckle, overhead lines sag, road asphalt soften and deform, and maintenance activities become more difficult.

“The issue is not the peak temperature but the duration.  Infrastructure has less opportunity to cool down and recover, while repeated thermal loading accelerates degradation and increases the likelihood of service disruptions.

“Vulnerabilities are not limited to individual assets but also arise from interdependencies between infrastructure systems.  Transport networks are vulnerable to heat-related impacts such as rail buckling, overhead line sagging and road surface deformation.  At the same time, heatwaves often increase electricity demand due to cooling requirements in buildings, transport hubs and data centres, placing additional stress on the power system.  Disruptions can therefore cascade across sectors, affecting transport operations, communications, supply chains and essential services.

“Many parts of the UK’s transport network were designed for the climate of the past, not the climate we are now experiencing.  The growing need for rail speed restrictions during heatwaves is a clear indication that some assets are already operating close to, or beyond, their original design assumptions.

“The focus is often on individual assets rather than interconnected systems.  A heatwave affecting transport can also disrupt energy, communications and supply chains.  In evidence recently submitted to the National Resilience Committee, we highlighted the need to move beyond hazard-specific approaches and adopt a whole-system, resilience-based perspective that considers cascading impacts, recovery capability and long-term adaptation.”

Prof Maarten van Reeuwijk, Professor of Urban Fluid Mechanics, Imperial College London, said:

Why homes overheat and what people can do about it

“The biggest source of heat in many homes is often solar radiation entering through windows rather than the outdoor air temperature itself.  External shading and keeping blinds or curtains closed on sun-facing windows can be more effective than leaving windows open all day.

“Many people accidentally heat their homes by opening windows during the hottest part of the day.  Ventilating at night and in the early morning, then closing windows when outdoor temperatures exceed indoor temperatures, is often much more effective, particularly in heavyweight buildings where the structure can be cooled overnight.

Cooling technologies: what works and what doesn’t

“Fans cool people rather than rooms, but can provide substantial comfort at very low energy use.

“Not all air conditioners are equally effective.  Some portable units can end up fighting against themselves by cooling the room while drawing warm air back into the home.

Preparing UK homes for a warmer future

“Heatwaves are no longer rare events.  The challenge is not only coping with today’s heatwave but adapting homes for a climate where overheating becomes a regular occurrence.

“Relatively simple measures such as external shading, night-time ventilation, reflective roofs and better building design can often reduce indoor temperatures without relying solely on air conditioning.

“Air-to-air heat pumps are a central part of the UK’s decarbonisation strategy because they provide highly efficient heating in winter.  Less widely appreciated is that the same systems can also provide effective cooling during summer heatwaves, potentially offering a dual solution for future homes.

Our homes and infrastructure were designed for a different climate

“Much of the UK’s housing stock, transport infrastructure and public buildings were designed with winter cold as the dominant challenge.  As heatwaves become more frequent and intense, overheating in homes, schools, hospitals, rail networks and urban areas is becoming a major resilience issue.

“There is a risk that adaptation and net-zero programmes focus primarily on reducing winter heating demand without adequately considering summer overheating.  Future housing and infrastructure policy will need to address energy efficiency, thermal resilience and good air quality simultaneously.

“Heatwaves are not just a weather issue; they are increasingly a housing, infrastructure and public-health issue, with decisions made today likely to influence resilience for decades to come.”

Dr Rob Barthorpe, Senior Lecturer, School of Mechanical, Aerospace & Civil Engineering, University of Sheffield, said:

“The increasing frequency and severity of heatwaves should sharpen our thinking on how we meet our heating and cooling needs now and into the future.  While passive measures such as solar shading and natural ventilation will have a huge role to play there are many properties for which these will be insufficient on their own, particularly during prolonged hot periods.  The Climate Change Committee highlighted the importance of active cooling measures in their most recent assessment of climate risk (A Well-Adapted UK: https://www.theccc.org.uk/publication/a-well-adapted-uk/).  It is estimated that the number of air conditioning systems in UK homes has doubled over the past 3 years, but the vast majority of these systems have either been portable units or built-in systems providing cooling only.  The CCC report drew particular attention to the role that reversible heat pump systems may play in providing cost-effective cooling during warm periods, in addition to their primary role of providing highly energy efficient heating during the winter.  There is some subtlety here – for example, you can’t use a standard radiator to provide cooling, so you need to use a slightly different unit containing a small fan for the rooms you wish to cool.  There is also the question of how we provided the power needed by these active cooling systems, although local solar generation offers a near perfect solution to this challenge.  However, by considering heating, cooling, and local generation in the round – whether for individual properties, multioccupancy buildings or across entire neighbourhoods – there is an opportunity to make our buildings ready for the climate challenges ahead.”

Prof Stefán Smith, Professor of Energy Systems and the Built Environment, University of Reading:

“The UK is not prepared for the impacts of climate change.  Recent independent assessments make this clear.  The Climate Change Committee’s fourth Climate Change Risk Assessment found that around one-third of risks are now classed as “very high”.  It also concludes that current and planned adaptation measures are largely inadequate.

“In practical terms, this means extreme weather can damage critical infrastructure, cause irreversible losses, cost billions, and lead to thousands of excess deaths.

“Overheating in buildings is a key risk that now requires urgent action across England, Wales and Scotland.  Heatwaves are already becoming more intense, and millions of people are experiencing overheating in their homes.  Some adaptations are being introduced, but we still lack strong evidence on how effective these measures are, either on their own or in combination.

“Air conditioning is becoming more common in UK homes, with an estimated 8 to 19 per cent of households now using it.  However, around 80 per cent of purchases have been made since 2022, with uptake heavily concentrated in Greater London.  Air conditioning will be part of the solution, but when used at scale in a city causes extra local warming, further widening the gap between the air conditioning haves and have-nots.

“This points to a clear need for better long-term solutions.  Building design and urban planning must adapt to hotter conditions.  This includes making greater use of green and blue infrastructure to reduce heat in cities and improve resilience.”

Dr Reyes Garcia, Associate Professor in Structural Engineering, University of Warwick, said:

“As temperatures continue to climb during heatwaves, British homes are increasingly feeling like ovens.  The secret to surviving future summers lies in rethinking how our homes are built and insulated all year around.  We have to shift our focus from simply winter warming to summer cooling as well, so we can design homes that naturally resist heat waves.

“Two ways modern engineering can keep our homes cool (with links to my articles):

“1. Traditional walls made of solid bricks or concrete blocks act like sponges, absorbing heavy heat from the afternoon sun and slowly “baking” the inside of a home.  A few years ago we designed a prefabricated wall specifically engineered to fight severe heat in tropical and warming climates.  This new wall was designed as a layered “sandwich” structure using recycled aggregate concrete, expanded polystyrene and cement boards.  This unique combination disrupts the path of heat.  Heat cannot travel easily through the foam-and-air layers, so the walls act as a thermal shield.  We did some laboratory testing and also built a full scale house, and we showed that the wall can reduce internal wall surface temperatures by up to 5°C compared to standard brick-and-mortar walls.  This can make a huge difference in terms of comfort and electricity (mainly fans and AC) use, and eventually costs: https://doi.org/10.1016/j.conbuildmat.2024.135568

“2. We also normally think of insulation as a “duvet” to keep us warm in the winter, but it works just as well the other way around!  High-quality insulation acts as a shield, blocking the hot afternoon sun from heating our houses.  We are using Phase Change Materials (PCMs) as a thin “duvet” plastering, which effectively acts like microscopic built-in ice packs in walls.  PCMs are blended directly into plasterboard (or ceilings) and so when the house gets too warm during the day, these materials melt at a microscopic level, absorbing the excess heat and keeping the room at a comfortable temperature.  At night, when the outside air cools down, the PCMs solidify again, releasing the trapped heat safely when it is cool enough to open the windows.  It is a completely automatic and cost-effective way to avoid extreme indoor temperatures.  In our experiments we have observed that PCMs can reduce indoor temperatures by about 1-3°C: 10.1016/j.jobe.2023.108315

“By using better and cost-effective smart materials that block and/or absorb heat, we can keep British homes comfortable, sustainable and cool for years to come.”

Dr Nan Li, Reader in Lightweight Design & Manufacturing, Dyson School of Design Engineering, Imperial College London, said:

“Lightweight vehicle manufacturing refers to the design and production of lighter, more energy-efficient transport components.  For example aluminium or high-strength steel parts for cars, electric vehicles, trains or aircraft.  These parts are often made through carefully controlled forming and manufacturing processes, where small changes in temperature or material behaviour can affect final part quality.

“From a lightweight design and manufacturing perspective, I would emphasise that extreme heat is not only a problem for infrastructure in service; it can also affect the manufacturing systems that produce safety-critical transport components.

“In forming processes, ambient and tool/die temperatures can influence material behaviour, lubricant performance, friction, springback and dimensional inspection.  In our own forming trials, we have seen that changes in ambient conditions can affect process repeatability and part quality.  In a factory where the process window is already tight, an extreme heatwave could therefore increase the risk of scrap, rework or out-of-spec parts unless the environment is controlled or the process parameters are properly compensated and revalidated.

“This is why factory cooling should not be treated only as a comfort issue.  For precision and safety-critical manufacturing, thermal control is part of quality infrastructure.  During extreme heat, manufacturers should monitor process temperatures, increase inspection for safety-critical parts, and avoid informal parameter changes that have not been validated.

“More broadly, climate adaptation for transport should include the manufacturing chain.  It is not enough to ask whether the rail, road or vehicle can tolerate heat once in service.  We also need to ask whether the components are being manufactured, inspected and qualified under thermal conditions that reflect the climate they will increasingly face.”

Prof Xueyu Geng PhD, FICE, FGS, FHEA, CEng, Professor in Geotechnical Engineering, Built Environment and Sustainability Cluster Lead, University of Warwick, said:

How do buildings and transport networks cope with heat?

“When temperatures rise this sharply, and for this long, the effects ripple across everything we have built, our homes, our offices, our railways, our roads, the very ground beneath them.  Buildings struggle to expel heat they were designed to retain, and cooling systems are pushed beyond their capacity.  And beneath the surface, in the soils and earthworks that carry our transport networks, changes are happening that are invisible to the naked eye but deeply significant to those of us who study them.

“The rails that expand and buckle in the sun.  The road surfaces that soften under tyre loads.  And perhaps most critically, the earthwork embankments and slopes that have carried our trains and traffic for generations, and whose stability depends on a delicate balance of soil moisture, root systems and ground pressure that prolonged heat quietly but significantly disrupts.

Railway track buckling:

“Steel rail expands significantly in extreme heat: a 1°C rise in temperature causes roughly 11mm of expansion per kilometre of track.  Rail is installed with a ‘stress-free’ temperature in mind, and when ambient and solar-radiation temperatures exceed that threshold, the track can buckle laterally, what the industry calls a ‘sun kink’.  This is why speed restrictions are imposed on the network during heatwaves; it is not a precaution, it is a structural necessity.

Road surface degradation:

“Sustained high temperatures soften bituminous asphalt surfaces, leading to rutting, shoving, and, very visibly, tyre-contact marks at junctions and bus stops where vehicles sit under braking load.  These are not cosmetic issues; deformed surfaces affect drainage, vehicle handling, and the long-term structural integrity of the carriageway.

Embankment stability:

“Perhaps the least visible but equally serious risk relates to the earthwork embankments, the engineered soil structures that carry railways and roads across the UK’s landscape.  In normal UK conditions, vegetated embankment slopes benefit from what geotechnical engineers call ‘unsaturated soil suction’, a negative pore water pressure that gives soil additional strength beyond its basic material properties.  Plant root systems reinforce this further, binding the soil and drawing moisture through transpiration.  Prolonged extreme heat disrupts both.  As soil desiccates, it shrinks and surface cracking develops.  Vegetation under heat stress dies back and loses its root tension.  The embankment becomes, in engineering terms, progressively weaker, quietly, and without any visible warning sign at the surface.  The critical moment comes when intense rainfall follows: severely desiccated, cracked soil does not absorb water efficiently.  Water runs off the hardened surface, dramatically increasing erosion, while water entering the crack network can reach depth rapidly, creating sudden and significant changes in the stress state of the embankment, exactly the conditions that precede slope instability.

Are there any specifics related to this forecast heatwave that present engineering challenges?

“This week’s heatwave brings all of these risks into sharp focus simultaneously.  The Met Office has forecast peak temperatures of 38°C in southern England, potentially breaking the UK’s June record, with overnight temperatures remaining above 20°C, what forecasters call ‘tropical nights’.  Perhaps most striking is the humidity: dew points forecast at around 22°C this week, compared to single figures during the record-breaking 2022 heatwave.  And critically, this is not a single hot day, it is a sustained, multi-day event, with thunderstorms and intense rainfall forecast to follow as the heat breaks down.

“From a ground engineering perspective, every one of these factors matters, and they matter not just for managing today’s emergency, but across the entire lifecycle of infrastructure, from initial design through to long-term maintenance.  Temperature, humidity, duration, and the pattern of heat followed by intense rainfall are not just weather statistics; they are the conditions that determine how soils behave, how slopes perform, and how earthworks age.  What makes this moment particularly important is that we now have decades of climate data that allow us to understand these patterns and, increasingly, to predict what is coming.  The challenge is knowing what to do with that knowledge, especially for infrastructure that was built long before we understood what today’s climate would look like.  Modifying or retrofitting existing earthworks, embankments and transport structures is far more complex and constrained than designing new ones from scratch.  Existing assets have fixed geometries, live operational pressures, and physical limitations that make adaptation genuinely difficult.  Yet that is precisely the challenge we must face, because the infrastructure that Britain built first, and that has served us longest, is also the infrastructure most exposed to a climate it was never designed for.”

John Lawrence, Chair of the IET (Institution of Engineering and Technology) Railway Technical Network, said:

“Heat is a significant issue for the railway, affecting both infrastructure and trains.

“Managing it is a cross-industry exercise running all year round, built into the seasonal preparation carried out by maintenance teams and planners across the network.  The areas hit hardest by heat also tend to cause the most disruption.

“Ambient temperature and solar gain combine to push temperatures very high at track level and in trackside equipment.  Track buckles and dewirements are what really worry engineers – despite years of focus, investment and improvement, rails can still buckle in extreme heat.

“That brings derailment risks, and overhead lines can sag and catch on pantographs, halting train movements or forcing lengthy reroutes.

“There are hidden failures too.  Signalling control, power supplies and trackside telecoms can all suffer heat stress, and rail expansion can cause switch-creep that stops trains being routed through points safely, so a signalling failure a passenger sees may actually trace back to overtemperature elsewhere on the network.  Lineside fires, sparked by anything from discarded rubbish to passing trains, can cause further disruption.

“These issues are costly and time-consuming to manage, and they’re becoming more frequent as high temperatures increase.  You might notice rails painted white to reflect solar gain at known risk points, upgraded tensioning equipment on overhead line gantries, fresh ballast to keep rails in place, and lubricated joints to allow for expansion.

“What passengers don’t see is the hidden technology tracking conditions and flagging early warning signs – weather forecasting across short, medium and long timeframes to help planners react; rail stressing to maintain consistent tension; vision systems checking pantograph contact; yellow trains monitoring track stability; temperature sensors on the rails; and points and signalling systems checked for defects.

“It might also surprise people that thermal imaging drones and helicopters are used to spot overheating equipment, with inspections and repairs often carried out overnight.

“Temperature management is a major issue for the railway and a constant focus of research and development.  With the climate changing, it’s an issue we now have to manage every day.

“One of the simplest ways we tackle overheating tracks is by painting them white, which can lower track temperature by 5°C and cut the signalling failures that cause major disruption.  It’s a technique used elsewhere too, in countries more used to high temperatures – in Italy, for instance, engineers often paint the inside faces of rails white to reflect sunlight and reduce the risk of buckling.”

Prof Lucelia Rodrigues, Head of Department of Architecture & Built Environment, Professor of Sustainable and Resilient Cities, University of Nottingham, said:

“The biggest threat from current and future heatwaves may not be outside since in the UK we spend 90% of our time indoors.  Better design, not more technology, is the key to protecting health in a warming climate.

“The solution to make buildings comfortable is not expensive or energy-intensive technologies – it is better design.  Climate change is increasing the frequency, duration and intensity of heatwaves in the UK, making overheating in buildings a critical challenge for the future.

“Many UK homes were designed to retain heat during winter and can become dangerously hot during prolonged periods of warm weather.  Yet creating homes that remain comfortable throughout the year does not have to cost more.  By designing buildings that respond intelligently to the climate – making the most of winter sunshine, providing effective summer shading, encouraging natural ventilation and reducing unwanted heat gain – homes can maintain comfortable temperatures with minimal energy use.  When a home works with the climate rather than against it, low-energy technologies can efficiently provide any additional heating or cooling required, creating healthier, more resilient places to live.”

Dr Antonios Kanellopoulos, Reader (Associate Professor) in Innovative Construction Materials, and Director of the Centre for Engineering Research, University of Hertfordshire, said:

“Most domestic buildings in the UK are optimised for keeping heat in and not out, which practically means use of heavy insulation, well-sealed building envelopes and minimal external shading.  In a heatwave, houses can turn into an oven, affecting the comfort levels of inhabitants.  Short-term solutions to improve comfort can include: use of curtains to block south or west facing windows (such windows in direct sunlight can emit ~700 Watts per square meter; almost like a small electric heater), use of external shading if possible (e.g. large patio umbrellas) and ventilate through wide open windows during the cooler parts of the day (evenings and early mornings).  Looking into the future and since these phenomena are becoming more often, the solutions should be more drastic involving adoption of the “passive house” principles.

“In the civil infrastructure things are slightly more complex under extreme heat conditions.  In the railway network, rail-tracks are installed under tension at a specific “stress-free temperature” (typically this is around 27oC in the UK) so the track sits in compression when it gets hotter.  Rail temperatures can be 20oC above air temperature in direct sun, and at that point compression can cause lateral buckling (i.e., a sideways bending and twisting) the so-called heat kinks.  That is the reason why Network Rail imposes speed restrictions in heatwaves, and why some rails are painted white: reflective paint can shave 5 to 10oC off rail temperature.  Roads have a similar problem.  Asphalt softens and ruts under heavy vehicles; concrete slabs can buckle upwards at expansion joints.  Airport runways have the same problem at scale, which is what happened at Luton in 2022.

“Bridges are generally designed with expansion joints and bearings to absorb thermal movement, so they usually cope well under extreme weather.  Overhead electrical lines, both railway catenary and grid transmission, can sag when hot, reducing clearances and current-carrying capacity exactly when demand spikes during the day.

“The engineering issue underneath all of this is that design codes are calibrated against historical climate data, and the historic temperature distributions have shifted.  Updating standards (for rail neutral temperatures, building cooling loads, drainage for heavier rainfall etc.) is now active work for engineers and standardisation bodies.  Retrofitting is harder and more expensive than designing in heat resilience from the start, which is why this is increasingly a planning and procurement question, not purely an engineering one.”

Dr Julie Godefroy, Head of Net Zero, CIBSE (Chartered Institution of Building Services Engineers), said:

How do buildings cope with heat?

“A large part of the stock (houses, flats, apartments, bedsits, maisonettes) is not prepared, as it was not designed and build to cope with such high temperatures for such long periods of time.  For example, the large majority of the housing stock does not have external shading devices, so solar gains can be high and create overheating risk even outside of heatwaves.  Urbanisation compounds the issue, with temperatures remaining high at night in city centres.

“In short, solutions include: high priority: reduce solar gains, and get rid of the heat through ventilation (open windows).  Other measures, such as reducing gains from electrical appliances, cooking, hot water tanks etc also help but to a smaller effect.  As a last resort, you may need to install cooling.

“Solutions in the short term include: use external shading if you have it, if not consider installing temporary shade (e.g. fixing a sheet outside the windows) – if not, at least use internal blinds / curtains.  Open the windows when it is relatively cool (e.g. mornings, nights if the window can be left open safely and securely), close it when it is hot outside – in that situation, internal fans (ceiling, ideally) can help with comfort); reduce other internal gains e.g. do not let electric things on that don’t need it (e.g. plasma screens).  If your home is on more than 2 levels, open windows at the bottom and top levels, ideally on opposite sides; if it is on one level, if available open windows at opposite sides or if not, as a corner: this will help drive air through and out.

“In the medium term, prepare your home for the next heatwave, i.e. consider installing permanent shading, and windows that can be left open safely at night (e.g. with grilles, or high level windows with a small opening), and take measures that will also reduce energy use e.g. insulating your water tank.  Consider installing ceiling fans, if your ceilings are high enough (typically more than 2.8m).  Also look around your home, as hot external surfaces nearby can increase the risk inside (e.g. painting with light reflecting materials can help), while vegetation or other ways to provide shade will help.

“More detailed guidance: CIBSE TM59¹ provides an assessment methodology to assess overheating risk through modelling, targeted at designers and modellers.  The Good Homes Alliance provides a free simple tool on assessing and reducing risk in existing homes, targeted at non-specialists like homeowners.”

1 https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-59-design-methodology-for-the-assessment-of-overheating-risk-in-homes?id=a0q0O00000DVrTdQAL

Dr Jess Neumann, Associate Professor of Hydrology, University of Reading, said:

“Just a few months ago we were talking about one of the wettest winters on record, yet following an unseasonably dry spring and now a second, potentially record-breaking heatwave, concerns are being raised around a potential risk of drought this summer.

“Hot weather is pushing our demand for water well beyond what is normally expected in June.  Keeping cool and hydrated, taking more showers, filling paddling pools, and watering gardens all add pressure to our water resources.

“The effects of extreme heat and low rainfall on rivers, wildlife and our environment are already in motion.  Many rivers and some reservoirs across the south have notably low flows, increasing pressure on aquatic life and raising concentrations of water pollutants harmful to wildlife and human health.  A prolonged lack of rainfall coupled with extreme heat further impacts agriculture and food production potentially driving up costs later this summer.

“It is never too late to be mindful of our water use.  Hot weather increases demands on water resources.  Small actions such as turning off taps, collecting rainwater (when it comes) for use on plants, using a watering can and taking fewer, shorter showers can all help reduce our individual water footprints.

“In previous years water companies have been accused of “sleeping at the wheel” with regard to water management.  Remaining attentive to the current water situation is vital if we are to ensure a safe and ready supply of water for society and the environment.”

Ruth Shilston MBE FIMechE, IMechE Trustee and Global Discipline Lead – Mott MacDonald, said:

“The UK is experiencing more frequent and intense heatwaves which can reduce productivity, disrupt infrastructure and even lead to shutdowns.  Managing comfort in the UK’s existing building stock is challenging; it was largely designed for winter conditions, leaving many prone to overheating during prolonged hot spells.

“The engineering response considers our cities as a system.  This includes reducing the ‘urban heat island’ effect through increased green spaces and planting of trees, with networks of cool spaces providing support to residents and visitors alike.  Adaptation at a building level is focused on low-carbon solutions such as natural ventilation, shading and reflective materials.  Other solutions involve designing buildings and infrastructure to better manage heat without relying heavily on energy‑intensive air conditioning.

“The greatest challenge is not just single peak temperatures but prolonged heatwaves and warm nights, which prevent systems and building fabric from cooling.  This creates cumulative strain on assets, buildings and services – as well as on the people using those assets, buildings and services.

“To respond, the UK needs sustained investment in infrastructure and public spaces so that out buildings, transport systems and cities are designed to cope with future heat.”

Dr Chengzhi Peng, Senior Lecturer in Architectural Science, University of Sheffield; and Principal Investigator of a NIHR-funded study on heat-resilient paediatric care, said:

“This week’s forecast temperatures near 38°C, oppressive humidity and nights that won’t fall below 20°C in our cities, is exactly the kind of event that puts hospital buildings under strain, and children’s hospitals are among the most exposed.

“Children are not simply small adults when it comes to heat.  Their bodies regulate temperature less efficiently, and the youngest and sickest patients, including babies in neonatal units, children in intensive care, have the least capacity to cope.  Many hospital wards were never designed for sustained heat like this.  They hold onto warmth overnight, so the building never gets a chance to cool down, and the spaces that overheat first are too often the ones caring for the most vulnerable patients.

“In the immediate term, the single most useful thing is knowing which wards and rooms overheat, and how fast, so staff can protect patients there first, such as moving vulnerable children to cooler areas, prioritising hydration, and using shading and overnight ventilation where it’s safe to do so.  The harder, longer-term task is adapting the buildings themselves, through better shading, insulation and passive/active cooling, so they remain safe during and days after heatwaves.  Our work with Sheffield Children’s Hospital and partners across the country is mapping precisely where these risks sit, and what most effectively reduces them.”

Prof Mujib Rahman, Professor in Civil Engineering in the School of Engineering and Innovation at Aston University, said:

“With the Met Office issuing a red heat warning this week, the extreme temperatures are a reminder that climate change is placing increasing pressure on our aged road network.

“Around 90% of UK roads are surfaced with asphalt, and globally there are over 40 million kilometres of paved roads, the majority of which are asphalt.  While air temperatures may reach 35°C this week, road surfaces exposed to direct sunshine can exceed 60°C.  At these temperatures, roads can soften, leading to wheel-track depressions (rutting), surface deformation and, in some cases, the road surface becomes shiny and slippery (bleeding).

“Repeated cycles of extreme heat followed by cooler and wetter weather accelerates pavement damage and significantly increases pothole formation, increasing maintenance costs and disruption for road users.

“At Aston University, our researchers are developing more durable road repair materials, thermally efficient road surfaces, and low-carbon, climate-resilient pavement technologies to help road infrastructure better withstand the challenges of a warming climate while reducing environmental impact.”

Anna Harrison, applied Quaternary scientist, BGS, said:

“Many soils contain clay minerals that absorb water and swell when they get wet, or lose water and shrink as they dry out.  Extended periods of dry weather and high temperatures are a major factor in the emergence of shrink–swell subsidence.  Looking ahead, these increases in hotter, drier summers and warmer, wetter winters are projected to continue.  Shrink–swell ground movement is one of the most damaging natural hazards in the UK today and presents a significant and growing economic cost.  Using Representative Concentration Pathways (RCP) climate projection data, we can see that this has the potential to affect millions of British properties in the coming decades.”

Jo Parker MBE C Eng. FICE FIWater FCIWEM, Director of Watershed Associates, said:

“The forecast heatwave will see water companies working flat out to maintain supplies.  In hot water people fill paddling pools, water the garden and take more showers which pushes demand up to maximum levels.  Whilst stocks of raw water are good, the demand can put a lot of stress on the distribution networks, requiring pumps to work at maximum capacity and with pipes reaching their full carrying capacity.  The networks are usually designed to cope with this.  However, the hot weather can lead to problems with the water companies’ extensive network as it leads to a weakening of road surfaces and movement of the underlying ground which in turn can lead to more failures in the pipe networks.  All the repair teams will be working flat out during the hot weather so bear a thought for them.  However hot it is they must continue to wear the required protective clothing to meet health and safety requirements and although much of the work is mechanised, some hand digging may required making it hot work.”

Prof Guy Gratton, Professor of Aircraft Test and Evaluation, Cranfield University, said:

“Aviation obviously operates completely in the atmosphere and is thus affected by the condition of air, including air temperatures.

“Before flight, a major challenge can be getting a sun-soaked airliner cabin cool before flight.  The air conditioning systems built into airliners are usually able to keep the cabin cool, but may need help to get it cool before flight.  This can be done by connecting the aeroplane to an external air conditioning unit, or by running the aircraft’s APU or Auxilliary Power Unit: a small (and rather noisy) jet engine located in the tail to run the onboard air conditioning at full power before flight.  This can all be done, although particularly in a usually relatively cool country like Britain there may not be enough external air conditioning units to go around.  The result of all of this tends to be more noise and pollution, which is clearly regrettable.

“During take-off and landing, the hotter air has lower density, and that means an aeroplane has to achieve higher groundspeed before it can take-off, or conversely it can have to be at a higher groundspeed during the final approach and landing.  A consequence of this is either that the take-off and landing distances tend to be longer, or from shorter runways the aeroplane can become payload limited, sometimes requiring the airlines to reduce the number of passengers on board.

“That also tends to create flatter climb-outs after take-off, which is regrettable for people living or working around any airport, as this will increase the noise footprint underneath the airliner climb-out path.  Higher temperatures therefore increase noise around airports.”

Anni Feng, built environment expert and Co-Chair of the IET’s Digital Futures Policy Centre, said:

“When it’s really hot outside, many of us feel uncomfortable indoors too.  That’s not just because of the building itself, but also because of what’s around it.

“Think of it like this: buildings don’t stand alone.  The materials used in roads and nearby buildings can trap heat, making the whole area hotter.  This extra heat can make people try to cool things down with fans or turn up air conditioning units.

“But if too many people do that at once, the local energy system might struggle to keep up.  That can lead to problems like cooling systems not working properly, which could even affect things like computers and other equipment inside buildings.

“Achieving climate resilience in the built environment requires holistic, systems thinking.  It demands a broad approach to understand how buildings, people and the wider environment interact, and to design for future climate conditions while working towards integrated, long-term solutions.

“When considering how we adapt for hotter temperatures, we should ask the questions like what this might mean for surrounding buildings, the environment and people in the communities – both short term and long term – and are they contributing positively to the future we aspire to create.”

Prof Barbara Rossi, Associate Professor of Engineering Science, University of Oxford, said:

“Before reaching for air conditioning, we should start with the measures that keep heat out in the first place such as external shading to stop direct sun hitting the windows, especially on south-facing facades and patio areas.

“There are affordable solutions online that can be placed (even just fabric) on e.g. roof windows and on skylights quite easily.  Electric motorised awnings, or even outdoor shade sail, especially on south-facing facades and patio areas that can reduce the temperature inside the house by several degrees thanks to shade projection through windows.  Good use of cross-ventilation in the cooler morning hours can make a huge difference for very little cost if one does it intelligently (cross-ventilation in the morning then closing south facing windows afterwards).

“Once those passive measures are in place, if cooling is still needed, I would like to underline that the priority should be given to highly efficient cooling unit that is built to last and uses as little electricity as possible.

“That is the sensible, low-carbon solution: reduce heat gain first, then cool efficiently only where necessary for as little time as possible.

“UK cannot afford cooling units running around the clock for two weeks a year, because that can add a great deal of greenhouse gas to the atmosphere, especially if the electricity mix is still not fully green.”

https://weather.metoffice.gov.uk/warnings-and-advice/uk-warnings#?date=2026-06-22

https://www.metoffice.gov.uk/about-us/news-and-media/media-centre/weather-and-climate-news/2026/extreme-heat-warning-extended-as-temperatures-forecast-to-reach-38c

Declared interests

Prof Keith Bell: “1. I have 77 ordinary shares in National Grid.

2. My wife has 650 ordinary shares in National Grid

3. My Chair at the University of Strathclyde is sponsored by Scottish Power.  I receive no personal remuneration in respect of the sponsorship.

4. I am involved in ongoing work with the National Energy System Operator (NESO) to provide training.  I receive no personal remuneration for this.  (The University receives a fee).

5. I am involved in a publicly funded research project (“HVDC-WISE”) with many collaborators from Europe and the UK including SSEN.  I receive no personal remuneration for this.  (The University receives a fee).

6. I am involved in a research project (“MOSAIC”) funded through SP Energy Networks’ ‘Network Innovation Allowance’.  I receive no personal remuneration for this.  (The University receives a fee).

7. I am a member of the Climate Change Committee.

8. I am a member of the Scottish Energy Advisory Board convened by the Scottish Government.  I receive no personal remuneration for this.

9. I am a member of NESO’s Engineering Advisory Council.  I receive no personal remuneration for this.

10. I am a member of Ofgem’s climate resilience expert panel for which I am due to receive remuneration of £800 per year.

11. In the past, I have led or undertaken research projects funded by Scottish Power, National Grid or SSE (for which I received no personal remuneration).  I retained full editorial control over reports.

12. Also in the past, I have carried out consultancy work for what is now NESO for which I received a fee.

13. I was an employee of National Grid between September 1998 and August 2005.”

Prof Stefan Doerr: “No conflicts of interest to declare.”

Prof James Allan: “Nothing relevant to this.  I’ve got active industry funding from Heathrow regarding environmental impact assessment, and had previous industry funding regarding car exhaust emissions and characterising standards for toxicity analysis, but I can’t think of any way in which they are relevant to my quotes.”

Dr Thomas Smith: “I don’t have any links to declare.”

Dr Jessica Mee: “I have no conflict of interest to declare.”

Dr Malcolm Mistry: “I declare no conflict of interest.”

Prof Claire Steves: “No declarations of interest.”

Dr Steve Denton: “No conflicts to declare.”

Dr Raquel Nunes: “No conflict of interests.”

Dr Eunice Lo: “No conflict of interest.”

Dr Ruby Lieber: “Nothing to declare.”

Mark Apsey: “I am CEO of CivicNetZero, a platform supporting cities to deliver net zero infrastructure.  I am an Honorary Professor at the University of Exeter, Past President and Trustee of IChemE, and a member of the Royal Academy of Engineering’s Clean Power Advisory Working Group.  These comments are made in a personal capacity.  I have no commercial interest in cooling or building products.”

Prof Jesus Lizana: “I confirm that I do not have any conflict of interest on this topic.”

Prof Sukumār Natarājan: “For any of your own research:

“The work related to weather files has received UK Research and Innovation (UKRI) funding for the UK data and joint UKRI-DST (Department of Science and Technology, Government of India)  funding for the India data.  Both are hence government funded research.  Other linked funders (i.e. parts or offshoots of the research) are the Coalition for Disaster Resilient Infrastructure (CDRI) and The British Council, both ’third sector’ organisations.

There were several industry partners in the above research.  No funding was received from them, though they did provide their time in-kind.  Their role has been as users of our work and in some cases, helped check intermediate stages of our work (Design Builder and SWECO).  Some industry partners in India helped organise some outreach workshops to interface with others and we disbursed their costs towards this.

To attend scientific meetings:

As above.

Current or previous advisory roles or committee membership:

I am on the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) GPC-49 technical committee that is writing a report on the use of future weather files.  This is an industry-body based in the US and responsible for a lot of the guidance used all over the world.

Previous employment in companies:

None.

If you have received industry funding for some of your other research, even if it’s not directly linked to this particular story, please include that too:

No.”

Prof Maarten van Reeuwijk: “I don’t have any conflicts of interest to declare.”

Dr Rob Barthorpe: “I have received funding from EDF for consultancy projects exploring optimisation of low carbon technologies in homes.  I am currently leading a project exploring the potential of low temperature heat networks with integrated thermal storage – this is funded through the South Yorkshire Sustainability Centre and Grantham Centre, with equipment provided by Daikin and project management support from E.On.  I led a major DESNZ-funded grant (ADSorB) that included Mixergy Ltd as a project partner.”

Dr Neil Maxwell: “I do not believe I have any conflicts of interest to declare.”

Prof Stefán Smith: “I do not have any conflict of interest as I see it.

For transparency, and any doubt, I declare I was a contributing author to the UK’s CCRA4 Independent Assessment and I have received and am in receipt of UKRI funding (https://www.ukri.org/what-we-do/) in support of some of my research at the University of Reading.”

Dr Alan Dangour: “No interests to declare.”

Dr Reyes Garcia: “No COIs.”

Dr Nan Li: “I have no relevant conflicts of interest to declare.”

Prof Xueyu Geng: “No commercial relationships or other positions.”

John Lawrence: “No conflicts.”

Prof Lucelia Rodrigues: “No conflicts of interest.”

Dr Antonios Kanellopoulos: “I am CEng and CSci, member of the Institute of Materials, Minerals and Mining siting in their Construction Materials Group leadership team.  I am also a member of the Institute of Concrete Technology and a senior member of The International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM).”

Dr Julie Godefroy: “No relevant conflicts of interest.”

Prof Hayley Fowler: “Funded by MRC, EPSRC, NERC, UKRI, Royal Society.

Industry funding from Gallagher Re.

Chief editor of frontiers in interdisciplinary climate studies.

Chair of Hadley centre climate programme science and advisory group.

Member of the climate change committee (adaptation).”

Dr Jess Neumann: “None to declare.”

Dr Laurence Wainwright: “No interests to declare.”

Prof John Marsham: “I receive UKRI , NERC, Gates, FCDO and Met Office research project funding.”

Ruth Shilston: “None.”

Dr Chengzhi Peng: “No conflicts of interest to declare.”

Prof Mujib Rahman: “No interests to declare.”

Dr Mireia Ginesta: “None.”

Anna Harrison: “We have a data product which projects impact of shrink-swell subsidence for use by developers, lenders, insurers etc, which Anna Is involved in developing.  This is a BGS project however and not industry funded etc.  Otherwise no conflicts.”

Jo Parker: “I am currently working as a contractor for UK Water Industry Research providing project management services.  This is a not for profit membership research organisation.  I also work as a sub-contractor for a variety of small and medium sized civil engineering contractors providing quality assurance services.  I have my own company with my husband as the only other board member.  I am also currently board member of a new tech company, OXEMS, although this is in the process of being wound up.”

Prof Guy Gratton: “No relevant interests to declare.”

Dr Heather Massey: “Heather Massey is a in the Extreme Environments Laboratory at the University of Portsmouth and also a member of the Medical Advisory Board of the Ectodermal Dysplasia Society (https://edsociety.co.uk/).”

Anni Feng: “She works at Hoare Lea, a built environment engineering consultancy firm.”

Prof Lizzie Kendon: “None.”

Prof Barbara Rossi: “None.”

Prof Friederike Otto: “None.”

Prof Dann Mitchell: “None.”

Dr Linda Speight: “No conflict of interest.”

Prof Bill McGuire: “Bill McGuire is Professor Emeritus of Geophysical & Climate Hazards at UCL.  His new book is The Fate of the World: a History and Future of the Climate Crisis.”

Prof Richard Allan: “No conflicts of interest.”

Prof Liz Bentley: “No conflicts of interest.”

Dr Akshay Deoras: “I’ve no conflict of interest to declare.”

Dr Chloe Brimicombe: “No disclosures.”

For all other experts, no reply to our request for DOIs was received.