More than 40,000 people died in England and Wales from extreme heat between 1988 and 2025, according to new figures from the Office for National Statistics (ONS). The data shows 40,000 deaths in England and 2,070 deaths in Wales were associated with the hottest days over the 40-year period.
Heat-related deaths rising as climate warms
The ONS said the gap between deaths caused annually by cold and hot weather is closing, with heatwaves becoming more extreme due to climate change. This has been driven by an uptick in heat-related deaths in recent years. People aged 65 years and older were most vulnerable to both the hottest and coldest temperatures, the study found.
London and the south of England face the highest mortality risks during extreme heat, classed as temperatures exceeding 29C. Health impacts linked to extreme hot weather include circulatory diseases, respiratory conditions, and dementia, as well as related illnesses arising in care homes, nursing homes and assisted accommodation.
Cold weather deaths still higher overall
An estimated 138,944 deaths in England and 10,098 deaths in Wales were associated with the coldest days in the same period. Scientists have warned that heatwaves are becoming more intense, lasting longer and occurring more frequently as a result of climate change brought on by burning fossil fuels.
England is on track this year for the highest number of heat-related deaths since records began, according to estimates released last month by the UK Health Security Agency (UKHSA). More than 2,700 people died from heat-related causes during May and June’s record hot spells.
Spring heatwaves linked to human activity
Researchers from Imperial College London, the Met Office, and the London School of Hygiene and Tropical Medicine (LSHTM) estimated that there were 2,700 excess deaths in England and Wales over the first two heatwaves of 2026. More than two fifths (42%) of the fatalities from the spring heatwaves died as a result of the extra heat caused by human activity.
The study, which collected near-rapid estimates of deaths, examined the periods around the record-breaking heatwaves of May, when temperatures peaked at 35.1C, and June, which hit new highs for the month of above 37C and was accompanied by high humidity. Updated figures including this summer's five heatwaves are expected later this year.
