Europe’s summer heat is estimated to have contributed to 50,391 deaths across 854 cities in 2026, according to a research analysis by scientists at Imperial College London and the London School of Hygiene & Tropical Medicine. The researchers estimated that 32,619 of those deaths were linked to the additional heat caused by human-induced climate change.
The figures are statistical estimates, not a count of death certificates that directly identify heat or climate change as the cause. The researchers used temperature and mortality models to estimate how many deaths occurred under actual summer conditions and how that toll might have differed in a climate without human-caused warming.
The findings point to a growing public-health challenge as extreme heat affects cities across southern, western and northern Europe. They also highlight the limits of current preparations, particularly for older people and others who may struggle to stay cool during prolonged hot weather.
However, the figures cover selected urban areas rather than the whole continent. The researchers’ analysis also excludes a heat episode in May, meaning it does not capture the full warm-season burden.
What the researchers estimated
The research team estimated 50,391 heat-related deaths across 854 European cities between June and August 2026. Of those, 32,619 were attributed to the additional heat associated with human-caused climate change.
The estimated total was 71% higher than the 29,480 heat-related deaths calculated for the summer of 2022 in the same group of cities. The comparison uses modelled estimates produced within the research programmed, rather than complete national death counts.
The study covered urban areas in 30 countries, with a combined population of about 173 million people. That represents approximately 40% of the population across the countries included in the analysis—not 40% of every European resident regardless of location.
Rural communities and urban areas outside the 854 selected cities are not fully represented. The researchers have therefore cautioned that the results should not be treated as a complete count of heat-related deaths across Europe.
How climate change contributed to the toll
To estimate climate change’s contribution, researchers compared the summer’s actual temperatures with simulated temperatures in a world without human-induced warming. They then applied established statistical relationships between temperature and mortality to estimate the difference in deaths under the two scenarios.
The resulting estimate—32,619 deaths attributed to climate-change-related additional heat—describes the modelled difference between those scenarios. It does not mean that climate change was listed as the cause of death for each person.
Heat can worsen existing health conditions, including cardiovascular and respiratory illnesses. Its effects may also be missed when deaths are recorded because the immediate medical cause does not capture the role played by high temperatures.
The method aims to estimate that hidden burden across a population. But, like other modelling approaches, its results depend on the quality of the temperature data, the mortality relationships used and the assumptions behind the simulated climate without human influence.
A published study provides the longer-term context
A separate paper published in Nature Health on October 14 examined heat-related mortality in the same 854 European cities from 2000 through 2025. It estimated 430,365 heat-related deaths over those summers, including 233,626 attributed to human-induced climate change.
That study found the estimated share of heat-related deaths attributable to climate change rose from 39% in 2000 to 68% in 2025. It also identified the greatest average mortality burden in parts of southern and southeastern Europe, including Croatia, Malta and Romania.
The historical paper helps explain the wider trend: human-caused warming has increased the heat burden across the cities studied, while the oldest age groups have faced the greatest risk.
The exact 2026 totals require separate verification against the full paper or official release for the summer analysis. They should not be treated as though they were already contained in the historical study.
The hottest period carried a large share of the estimated deaths
Researchers identified a particularly intense period from June 17 to July 1. Across the cities studied, temperatures during that period averaged about 5.3 degrees Celsius above normal.
The analysis attributed nearly one-third of the summer’s estimated heat-related deaths to that period. Some locations experienced daily temperatures as much as 12 degrees Celsius above historical averages, according to the research account.
Italy had the highest estimated national total, with 13,303 deaths across the cities included in the analysis. France followed with 7,268, Spain with 6,824 and Germany with 6,340. These figures are estimates for the study’s urban areas, not complete national mortality totals.
The United Kingdom’s included cities accounted for an estimated 4,354 heat-related deaths, of which 2,535 were attributed to human-induced climate change. The results show that the health burden extended beyond Europe’s traditionally hottest regions.
Older people faced the greatest risk
People aged 85 and older accounted for an estimated 22,502 deaths—about 45% of the total. The analysis also estimated more than 800 deaths among adults aged 20 to 44, showing that heat-related mortality was not limited to the oldest population group.
Older adults may face greater risks because of underlying health conditions, reduced ability to regulate body temperature and social isolation. People who live alone, lack access to cooling or cannot easily leave overheated homes may be especially vulnerable.
Yet age alone does not determine risk. Outdoor workers, people with chronic illnesses, infants and those living in poorly insulated homes can also face serious dangers during heatwaves.
The findings reinforce the importance of identifying vulnerable residents before extreme heat arrives, rather than relying only on public warnings once temperatures have already risen.
Why the estimates are not official death counts
The researchers used statistical models because heat’s role in deaths is often not recorded directly. Their approach estimates the number of deaths associated with high temperatures and compares that estimate with a counterfactual scenario in which human-caused warming is removed.
That differs from official monitoring systems, which may estimate excess deaths during specific heat events using observed mortality data. The methods can provide complementary evidence, but their results should not be treated as interchangeable.
For example, England’s interim heat-mortality report estimated 2,877 heat-associated deaths during defined events in May and June 2026. The report used a national monitoring method focused on observed mortality during those periods, rather than the same pan-European climate-attribution framework.
Researchers involved in the European analysis have said their modelled estimates for the May and June heat events in England and Wales were broadly close to official monitoring estimates. Such comparisons can help assess the model, but they do not mean the two approaches measure precisely the same thing.
The distinction matters when interpreting the headline number. The 50,391 estimate is evidence of a substantial modelled mortality burden, not a final administrative tally of deaths officially registered as heat-related.
May heat is missing from the summer estimate
The 2026 analysis covers June, July and August. It excludes a heat episode in May, even though separate research estimated a substantial mortality burden during the earlier period.
In England, the UK Health Security Agency estimated 2,877 heat-associated deaths across heat episodes in May and June. Researchers from the London School of Hygiene & Tropical Medicine, Imperial College London and the Met Office separately estimated more than 2,700 heat-related deaths in England and Wales during May and June.
Those figures cannot simply be added to the European summer total. They cover different geographic areas, use different methods and include periods that overlap with other heat assessments. But they demonstrate why the June-to-August estimate should not be described as the complete toll for the entire warm season.
A full estimate would require consistent coverage of the relevant May events, the rest of the summer and the populations not represented by the 854 cities.
Public-health preparations need to match the risk
The findings point to several practical ways to reduce harm during future heatwaves. Public-health agencies can issue early warnings, contact older or medically vulnerable residents, expand access to cooling centers and ensure that hospitals and care homes have plans for prolonged hot weather.
Cities can also reduce exposure by planting shade trees, protecting green spaces, improving building insulation and ventilation, and designing public areas to limit heat accumulation. These measures are especially important in dense neighborhoods where buildings and paved surfaces can retain heat overnight.
Independent climate-and-health experts have also stressed the importance of combining adaptation with reductions in greenhouse-gas emissions. Cooling measures can protect people from some of the heat already expected, while limiting further warming can reduce future risks.
No single intervention can eliminate heat-related deaths. The most effective response depends on local conditions, housing quality, health services and whether vulnerable people can access help when temperatures rise.
A warning, with important limits
The estimated 50,391 deaths show the scale of the health burden associated with summer heat in the cities studied. The estimated 32,619 deaths attributed to additional heat from human-caused climate change underline the role of global warming in increasing that burden.
But the analysis does not represent every European community, excludes the May heat episode and relies on modelling rather than a direct count of death certificates. Its 2026 totals must also be checked against the full summer-analysis paper or an official research release.
The evidence nevertheless supports a clear public-health conclusion: cities need stronger systems to protect people during extreme heat. Early warnings, accessible cooling, neighborhood support and better-prepared health services can reduce immediate risks, while lower greenhouse-gas emissions can limit the additional heat that drives future danger.
Reporting Credit: Nature Health — published research on heat-related urban mortality attributable to human-induced climate change in Europe from 2000 to 2025. UK Health Security Agency — interim heat-mortality monitoring report for England covering May and June 2026. London School of Hygiene & Tropical Medicine, Imperial College London and the Met Office — research materials on heat-associated mortality during the May and June 2026 heatwaves. The exact 2026 European summer totals remain pending confirmation against the full study or official release.
