More than 40,000 additional deaths in England were associated with extreme heat between 1988 and 2025, according to new figures from the Office for National Statistics (ONS), highlighting the growing threat posed by rising temperatures and climate change.
The data, released as England experiences one of its hottest and most challenging summers on record, shows that the number of people dying prematurely during periods of extreme heat has increased over time. Health experts have warned that the trend is likely to intensify as global temperatures continue to rise and the population becomes older and more vulnerable to heat-related illness.
The ONS figures do not include the deaths recorded during the current summer. Earlier estimates from the UK Health Security Agency indicated that 2,877 people died as a result of the heatwaves experienced in May and June alone. That figure is already almost twice the estimated number of heat-related deaths recorded during the entire summer of 2025, raising concerns that 2026 could become the deadliest year for extreme heat in England.
Older people are among those most vulnerable to prolonged periods of high temperatures, while children and people with existing health problems can also face increased risks. Extreme heat can worsen cardiovascular and respiratory conditions and place significant pressure on hospitals, emergency services and other public health systems.
England’s health services have already experienced exceptionally high demand this summer. Hospital emergency departments recorded almost 2.5 million attendances in each of May, June and July, with extreme weather identified as one of the factors contributing to the pressure. Emergency services in London have also reported a substantial rise in demand, with the London Ambulance Service receiving around 25,000 more calls this summer compared with the previous year.
The ONS analysis also found that the risk of dying increased significantly when temperatures rose above 24C across almost all English regions and Wales. London recorded the highest number of deaths linked to the hottest temperatures during the period studied.
Historically, cold weather has been responsible for considerably more excess deaths than extreme heat. ONS figures show that about 139,000 deaths in England were associated with the coldest days between 1988 and 2025. However, the difference between cold- and heat-related mortality has been narrowing as heat-related deaths increase.
In the latest year covered by the ONS figures, 2,805 heat-related deaths were recorded in England and Wales, compared with 2,244 associated with cold weather. Researchers said the changing pattern demonstrated how the health risks posed by rising temperatures are becoming increasingly significant.
Climate experts have warned that heat-related deaths could eventually overtake those linked to the coldest days if current warming trends continue. They have called for stronger measures to protect people from extreme temperatures, alongside faster action to reduce greenhouse gas emissions.
The UK’s ageing and often poorly insulated housing stock has also emerged as a concern. Experts say many homes were built for a cooler, temperate climate and can become dangerously hot during prolonged heatwaves. Improving housing standards, providing better cooling systems and strengthening public infrastructure could therefore play an important role in reducing future deaths.
Government advisers have previously recommended greater use of air conditioning and other cooling measures in hospitals, care homes and schools. They have also called for clearer protections for people working indoors and outdoors during periods of extreme heat.
The latest figures come amid growing evidence that climate change is making extreme weather events more frequent and severe. Europe has experienced a series of record-breaking heatwaves this year, with tens of thousands of excess deaths already reported across several countries. Scientists have linked the increasing intensity of these events to human-driven global warming.
Experts have stressed that the deaths associated with extreme temperatures are not simply an unavoidable consequence of hot weather. Better preparedness, early warnings, improvements to buildings and healthcare facilities, and measures to reduce exposure to extreme heat could save lives.
The findings have consequently renewed calls for the UK to strengthen both its climate adaptation policies and efforts to reduce fossil-fuel emissions. With temperatures expected to rise further as the climate changes, researchers warn that the deadly impact of extreme heat could become an increasingly familiar feature of summers in England unless stronger preventive measures are adopted.
