More than 2,700 people are thought to have died from heat-related causes during the May and June heatwaves in England and Wales.
Of those, it’s estimated that 42% died as a result of the extra heat caused by human-induced warming.
Researchers from Imperial College London, the Met Office and the London School of Hygiene & Tropical Medicine used historical mortality records and established peer-reviewed methods to model fatalities during both heat spikes. As Scotland and Northern Ireland were not impacted by such extreme temperatures, they focused on England and Wales.
Both events were record-breaking due to the impacts of climate change. The national record for May was broken when 35.1°C was recorded in West London, and three consecutive days of record-breaking June temperatures culminated with heat in excess of 37°C in East Anglia. Such high temperatures would be extreme even at the height of mid-summer, with July and August typically bringing the UK’s peak summer temperatures.
With the UK now regularly experiencing temperatures far beyond historical norms, the findings illustrate the importance of heat adaptation to protect the most vulnerable during future heatwaves, and underline the necessity of reaching net zero emissions globally.
About 550 people are estimated to have died due to heat related causes during the May heatwave (21-29 May 2026) and about 2,200 during the June heatwave (18-28 June 2026) in England and Wales.
Approximately 59% of the deaths in May, and 38% in June are attributable to the additional heat added by human-caused climate change. Across both events, that amounts to about 42% of heat-related deaths.
Daytime maximum temperatures across England and Wales are now roughly 3-4°C hotter than they would have been without human-induced climate change, raising the health risks associated with these heatwaves. Without this extra warming, temperatures of this severity would have been far less likely to occur.
While southern England saw the highest temperatures, estimates suggest the death rate (per million population) was similar in the Midlands. With this region less frequently exposed to extreme heat, it suggests residents there are more vulnerable to the impacts.
Dr. Clair Barnes, Research Associate in Extreme Weather and Climate Change, Imperial College London said:
“Every time we have a heatwave, our news is filled with reporters at swimming pools, images of people eating ice cream and sunbathers on beaches. We all love the sun, but people need to be aware that we are now seeing dangerous climate-change fuelled heat that is claiming lives, disrupting schools and hospitals and shutting down transport and infrastructure.
“It’s time we woke up to the fact that we now live in a country with dangerously hot summers. To protect people during future extremes, we must urgently adapt to the reality of the climate we now have, and double down on global efforts to reach net zero emissions to stop this from getting worse.”
Dr. Mark McCarthy, Manager of Climate Attribution at the Met Office said: “2026 has been exceptional for the two early season heatwaves in May and June. These have smashed records that had stood from May 1944 and June 1976 respectively. For the time of year these events were extreme, even in our warmer climate.
“However, it is clear that human-caused climate change is leading to more frequent and more intense summer heatwaves. This intensification is driving many impacts, including those affecting human health and mortality and other issues, such as agriculture, effects on transport infrastructure and biodiversity.”
Dr. Malcolm Mistry, Assistant Professor in Climate and Geo-spatial Modelling, London School of Hygiene & Tropical Medicine (LSHTM) said:
“We are still in the first half of summer in the UK and large parts of England and Wales have already experienced two record-breaking heatwaves, in May and June, triggering extreme heat-health alerts across England. With climate change driven by human activity making summer heatwaves more frequent and more intense, these spikes of extreme hot weather are rapidly evolving into a major health risk for people in the UK.
“It is vital that action on adapting Britain’s homes, workplaces, and critical infrastructure to extreme heat outpaces these health risks, especially if we are to protect those most vulnerable to its impacts, such as older people, babies, and children.”
Professor Lea Berrang Ford, Head of the UK Health Security Agency (UKHSA) Centre for Climate and Health Security (CCHS), said:
“These modelled estimates are based on past trends in temperature effects on mortality and provide an important indication of the potential health impacts of sustained hot weather, particularly for the most vulnerable among us. While they are not a measure of observed mortality, they help illustrate the scale of risk associated with extreme heat and the growing threat climate change poses to our wellbeing.
“As set out in our most recent Health Effects of Climate Change report, periods of heat in the UK are likely to become more intense, longer and more frequent as the world continues to warm. UKHSA continues to develop its guidance and evidence, working with partners to protect the most vulnerable in our society who are most likely to feel the impacts of hot weather, including through the Adverse Weather and Health Plan and the Weather-Health Alerting system.”
Gareth Redmond-King at the Energy and Climate Intelligence Unit (ECIU) said:
“Temperatures simply wouldn’t have been as high and whilst it’s particularly the vulnerable – the elderly, the very young, and less well-off who are least able to cope with the extremes that climate change brings, with NHS hospitals having to cut services, this poses a growing risk to everyone. In the here and now, air conditioning for hospitals and schools is a costly yet crucial next step, but the only way to halt climate change, and stop our summers getting hotter and hotter, and more and more deadly is to reach net zero emissions and bring balance back to the climate.”
