Researchers estimate 50,391 heat-related deaths across 30 European countries in summer 2026

Researchers at Imperial College London and the London School of Hygiene & Tropical Medicine estimate that heat killed 50,391 people across 854 urban areas in 30 European countries between June 1 and Aug. 31, 2026, with about two-thirds of those deaths linked to human-caused climate change.

The figure comes with an important caveat: It is not an official count from death certificates. It is a modeled estimate of heat-related excess deaths from an accepted manuscript released ahead of final journal publication. The analysis covers the 27 European Union member states plus the United Kingdom, Norway and Switzerland. The 854 urban areas in the study represent about 173 million people, or roughly 40% of the combined population of those countries.

To produce the estimate, the researchers compared observed daily temperatures in each city with temperatures in a counterfactual world without human-caused warming, then applied established temperature-mortality relationships to estimate heat-related deaths. That kind of modeling is widely used for heat because heat is rarely listed as the primary cause on death certificates, meaning official tallies and academic estimates often differ.

The study attributes about 32,619 deaths, or roughly 65%, to human-induced climate change. Nearly one-third of the estimated deaths occurred during a two-week stretch from June 17 to July 1, when mean temperatures across the study region were about 5.3 degrees Celsius above the 1991-2020 average. The burden fell heavily on older people: about 22,500 of the estimated deaths were among people age 85 and older. But the toll was not limited to the elderly. The study estimated roughly 6,000 deaths among people younger than 65, including more than 800 among adults ages 20 to 44.

“These numbers are a stark reminder that our hotter, more extreme summers are increasingly having a severe impact on public health,” Clair Barnes, the study’s lead author at Imperial College London, said in a press release issued by the London School of Hygiene & Tropical Medicine. “It is yet another reminder both of the urgent need to rapidly transition away from fossil fuels to slow the pace of change, but also the imperative of rolling out targeted interventions to protect those who are most vulnerable to the worsening extreme heat.”

In absolute terms within the study’s city sample, the highest country totals were reported for Italy, with 13,303 estimated deaths, followed by France with 7,268, Spain with 6,824, Germany with 6,340 and the United Kingdom with 4,354. Those figures are not full national death tolls; they reflect only the cities included in the study. At the city level, Paris, with about 2,545 estimated deaths, and Milan, with about 2,467, were among the highest totals reported.

The researchers said summer 2026 was the deadliest in their record for the same 854 cities from 2000 through 2026. Their estimate for this summer exceeded their earlier estimates for 2022, at about 29,480 heat-related deaths, and 2003, at about 28,462. In a peer-reviewed companion paper published Oct. 14 in Nature Health, the same team estimated 430,365 heat-related deaths across the same 854 cities from 2000 to 2025 and found the share attributable to human activity rose from about 39% in 2000 to 68% in 2025.

The new estimate has clear limits. It covers only the 854 urban areas in the study, not rural populations, and the headline total does not include an earlier late-May heat episode. Outside experts have also urged caution about interpreting modeled heat mortality. Lasse Vestergaard of EuroMOMO, the European mortality monitoring network, said the estimates “involve several uncertainties and assumptions.” Even so, the study points to 2026 as the worst summer for heat in this specific city-based record and argues that much of that burden now reflects anthropogenic warming, not just natural swings in weather.