Heatwave in Western Europe caused more than 10,000 additional deaths in late June, data shows

More than 9,000 of the additional deaths were people over the age of 65. Extreme heat can cause death by triggering heatstroke or by worsening cardiovascular and respiratory diseases, with older people being most at risk. Scientists said there were no other known major factors such as Covid-19 outbreaks contributing to the increase in deaths.

What the new research says

A separate scientific study published on Monday estimated that around 2,700 people in England and Wales alone died from heat-related causes during the heatwaves in May and June. According to results from Imperial College London, 42 percent of those deaths were caused by the additional heat resulting from global warming.

Climate researchers stated that the late-June heatwave would have been "virtually impossible" without human-caused climate change. The attribution reflects a growing body of rapid-attribution studies that have linked successive European summers to warming driven by greenhouse-gas emissions.

"Eine derartige Übersterblichkeit zu dieser Jahreszeit ist ungewöhnlich. Sie ist wirklich hoch," Vestergaard said, underscoring how unusual it is to see mortality of this scale outside the typical winter respiratory virus season. The week in question included several days of record-high temperatures across parts of France, Belgium, the Netherlands, Spain and the United Kingdom.

Who is most at risk

The findings add to concerns about how prepared European health systems are for heat events as the climate warms. Public-health authorities have repeatedly warned that older adults, people with chronic illnesses, infants and outdoor workers face the highest risk during prolonged heatwaves.

National heat-action plans vary widely across Europe. Some countries, including France and Spain, have introduced local warning systems, opened cooling centers and adjusted workplace rules during peak temperatures, but researchers say that adaptation measures are still uneven.

Mortality surveillance networks such as Euromomo, which is supported by the EU health authority ECDC and the WHO, are designed to flag unusual death tolls within roughly a week. The platform pools data from participating countries and compares weekly totals against a historical baseline for the same period.

How Europe monitors excess deaths

European summers have produced a series of deadly heat episodes in recent years, including in 2003, 2022 and 2023. Each event has prompted renewed calls for stronger building standards, urban greening and targeted outreach to older residents during heat alerts.

Scientists caution that the final death toll from this season's heat may take weeks to confirm as delayed registrations are added to national statistics. Early indicators, however, point to one of the most severe single-week heat-related mortality figures recorded in Europe in the past two decades.