Europe heatwave caused thousands of excess deaths, study finds

More than 10,000 excess deaths were recorded in western Europe during the late-June heatwave, and more than 9,000 of those deaths were among people aged 65 and older. The figures were still preliminary, and the EuroMOMO mortality network called them preliminary, but they already pointed to a death toll that has outpaced the normal seasonal average by a wide margin.

The losses were not evenly spread. Germany’s Robert Koch Institute estimated 5,120 heat-related deaths so far this year, with most occurring during the late-June period, while Germany’s Federal Statistical Office put excess deaths at more than 5,000 during the same heatwave. In France, the Netherlands and Belgium, the combined excess death count reached about 3,700, including about 2,025 in France at the peak of the heat and about 480 in the Netherlands.

A rapid analysis by Imperial College London and the London School of Hygiene & Tropical Medicine found that climate change made the June 23 to July 2, 2025 heatwave about 1 to 4C hotter and helped drive around 2,300 heat-related deaths across 12 European cities. The researchers found about 1,500 of those deaths were directly attributable to human-caused climate change and that the event killed nearly three times as many people as a cooler climate would have. People aged 65 and over made up 88% of the deaths in the city-level analysis.

Heatwaves remain “silent killers” because heat is rarely recorded as the direct cause of death and official mortality data can take months to publish. Early-season heatwaves can be especially dangerous because people have not yet acclimatised, leaving older adults and those with underlying illness at highest risk. Their city-by-city breakdown found the largest climate-linked tolls in Milan, Barcelona, Paris, London and Rome.