Heat-Related Deaths Surge Across Europe as Extreme Temperatures Push Human Bodies to the Limit
An estimated 50,391 people died from heat across 854 European cities during summer 2026, with 32,619 of those deaths attributed to additional warming caused by human activities, a study by researchers at Imperial College London and the London School of Hygiene & Tropical Medicine found. The findings were published in Nature Health.
The toll was 71 per cent higher than in 2022, the previous deadliest summer for those cities, when 29,480 people died. The proportion of heat-related deaths attributed to human-caused climate change has increased from about 45 per cent in the early 2000s to 65 per cent in summer 2026, according to the researchers.
The true toll is likely higher because the figures exclude a deadly May heatwave and cover cities with about 40 per cent of Europe's population. Heat deaths are often missing from death certificates, said co-author Garyfallos Konstantinoudis, a biostatistician.
Where and When Heat Struck
About one-third of the deaths occurred between 17 June and 1 July, when temperatures were 5.3C (9.5F) above normal. On some days, temperatures in certain European cities were as much as 12C (21.6F) above historical averages.
Italy, France, Spain and Germany recorded the highest death tolls. Rome had the highest heat death total of any European capital from 2000 to 2025, according to the researchers' earlier study.
Who Is Most at Risk
More than half of those who died were aged 85 or older. The heat also killed more than 800 people aged between 20 and 44.
The European Environment Agency says older people, children, pregnant women and people with heart, lung or kidney conditions are among those most vulnerable to extreme heat. Outdoor workers also face higher risk.
How Heat Harms the Body
Lead author Clair Barnes said Europe is 2.5C (4.5F) hotter than pre-industrial times. For many people, that extra warming can tip temperatures from uncomfortable to dangerous and potentially deadly.
The WHO advises using electric fans only when the air temperature is below 40C (104F), warning that they can increase heat stress when temperatures exceed that level.
Heatstroke is a medical emergency with a high case fatality rate. Deaths and hospital admissions can occur within the same day or the days that follow, so responses must be fast when a heat alert is issued.
Doctors at UT Southwestern Medical Center say heat exhaustion can cause headaches, dizziness, nausea and heavy sweating. Prompt treatment can help prevent the condition from worsening.
Heatstroke, however, is far more dangerous. By then, the body's temperature has risen so much that organs, such as the brain, are shutting down. Signs include confusion, agitation, slurred speech and seizures.
The priority in suspected heatstroke is to cool the person rapidly while seeking emergency medical assistance. A core body temperature of around 40C (104F) is a common sign of heatstroke, which can cause life-threatening complications.
Protecting People From Extreme Heat
WHO advises people to avoid strenuous activity during the hottest time of day, stay in the shade and drink water regularly.
Checking on vulnerable people, especially those over 65 or living alone, is also advised. A cool shower or bath, or time in air conditioning, is a much better way to cool off than fans alone, says the American Red Cross.
Dr Courtney Howard, an emergency room physician and president-elect of the Canadian Medical Association, urged investment in heat early-warning systems and neighbourhood buddy systems to check on people most at risk. She was not part of the research.
Dr Jonathan Patz of the University of Wisconsin-Madison, who was not involved in the research, said adaptation alone would not be enough. He called for measures including better access to cooling and greater protection for vulnerable populations.