Researchers at the London School of Hygiene & Tropical Medicine and Imperial College London have estimated that 50,391 heat-related excess deaths occurred across 854 European urban areas during the summer of 2026.
The figure covers June to August and is a modelled estimate rather than a count of deaths in which heat was entered as the cause on a death certificate. The work examined cities in 27 European Union countries, as well as the United Kingdom, Norway and Switzerland. Those 854 areas represent about 40% of the population across the 30 countries included in the analysis.
The researchers estimated that about two-thirds of the heat-related excess deaths, or 29,330, were attributable to human-induced climate change. Their estimate for all heat-related excess deaths had a 95% empirical confidence interval of 46,026 to 53,878. The climate-attributable estimate had an interval of 23,495 to 34,420.
How the estimate was produced
The analysis combined daily temperature data with city- and age-specific evidence on the relationship between temperature and deaths from all causes. Researchers assessed conditions in the 854 urban areas between 1 June and 31 August, using weather observations and climate models.
They compared temperatures in the present climate, which has warmed globally by about 1.4°C, with a counterfactual climate without human-caused warming. The two temperature scenarios were then used alongside established temperature-mortality relationships to estimate the mortality associated with heat in each case. The difference between the two estimates was treated as the share attributable to climate change.
This approach is designed to estimate the population-level health burden associated with summer temperatures. It does not identify which individual deaths were caused by heat, nor does it replace national mortality registration. The estimates depend on assumptions about exposure and on historical evidence about the association between local temperatures and mortality.
Where and when the burden was greatest
Southern and western Europe experienced the highest temperatures and estimated mortality rates in the study. Western Europe had the largest temperature anomaly, with average temperatures about 2.9°C above the 1991 to 2020 average. On some days, temperatures were up to 12°C above the seasonal average.
Nearly one-third of the estimated deaths occurred between 17 June and 1 July, a period when average daily temperatures across the region were more than 5°C above the 1991 to 2020 average. The analysis also found a substantial estimated burden in northern European areas that have historically had cooler summers.
Across the 135 UK urban areas included, the researchers estimated about 4,500 heat-related deaths. They estimated that about 6,000 of the deaths across the full study area involved people aged under 65, while older adults were the most affected group overall.
A comparison with earlier summers
Within the study’s 2000 to 2026 period, summer 2026 produced the highest estimated heat-related death toll. The estimate was well above those for 2022 and 2003, which were about 29,480 and 28,462 respectively under the same broad analytical framework.
A related retrospective analysis of summers from 2000 to 2025 estimated more than 430,000 heat-related deaths across the same urban areas. It found that the estimated proportion attributable to human-induced climate change rose from roughly 40% in 2000 to more than two-thirds by 2025.
The new findings describe a large estimated public-health burden across European cities during a single summer. They should be read as an assessment based on observed temperatures, climate modelling and historical mortality relationships, with the stated uncertainty ranges, rather than as a definitive record of individual causes of death.
