June 21, 2025

expert reaction to a real-time rapid analysis of heat-related excess mortality for 19-22 June 2025

Scientists comment on a real-time forecast of heat related deaths during the 19-22 June 2025 heatwave.

Prof Hannah Cloke, Professor of Hydrology, University of Reading, said:

“This is a simple, rapid analysis that uses an already understood relationship between heat and excess mortality, and applies the numbers from the ECMWF forecast for average daily temperatures for this weekend. While this isn’t peer reviewed science, it does highlight something we already understand well, that hot weather over a long period kills people. Every one of these figures is an individual person, with a family and a community that will be devastated by their early death. This is no less a tragedy than a plane crash or an outbreak of a deadly disease.

“Climate change is making heatwaves more common, longer and hotter in the UK, but no-one should die because they are unprepared for hot weather or because their home heats up and kills them. While we should urgently curb emissions to reduce the heating of our planet, saving lives in the future, we can save lives now by adapting our homes and practices so that people don’t die needlessly in hot weather. With better planning, building regulations, and early warnings leading to action, we can stop people from getting dangerously overheated and dying.

“The study notes a limitation that it does not consider temporal attenuation of temperature. Hot weather is less dangerous if you are able to cool off. You could save a life by checking on a vulnerable or elderly person and helping them to cool down, if just for a few hours. Shading windows or changing your plans to avoid the fiercest daytime heat could be the difference between life and death.”

Dr Chloe Brimicombe, Climate Scientist and Heat Specialist and Freelance Consultant, said: 

“This real time analysis although alarming is accurate and can be taken into account through syndromic surveillance (real time tracking) by the health service. It is consistent with patterns we see with other UK heatwaves and is good to see this transparency. 

“Heatwaves might be silent killers but they also subtly impact every part of our society from how we shop to hospital admissions to productivity and our pets and wildlife too. And we need a policy response that brings everyone together and tackles it across society not just the health sector.” 

‘Real-time forecast of heat-related excess mortality during the 19-22 June 2025 heatwave in England and Wales’ by Garyfallos Konstantinoudis et al. was published at 00:01 UK time on Saturday 21 June.

Declared interests

Prof Hannah Cloke: “works with and advises the Met Office and Environment Agency and a Fellow of ECMWF which provided the forecast data used in the study.”

Dr Chloe Brimicombe: No disclosure.