More than 50,000 people are estimated to have died from extreme heat in European cities during the summer of 2026, according to two peer-reviewed studies published in Nature Health. Researchers from Imperial College London and the London School of Hygiene & Tropical Medicine analyzed temperature data and mortality patterns across 854 urban areas in 30 countries—27 EU member states plus the UK, Norway, and Switzerland—which collectively represent about 40 percent of those countries' populations.
The death toll of 50,391 is the highest in at least 26 years and substantially exceeds previous major European heat waves. The 2022 heat waves caused an estimated 29,480 deaths in the same urban areas, and 2003 saw approximately 28,462 deaths. Nearly two-thirds of this summer's deaths—about 32,600—are directly attributed to climate change caused by the burning of fossil fuels, the researchers concluded.
Western Europe experienced its hottest summer on record, with temperatures averaging 2.9 degrees Celsius (5.2 degrees Fahrenheit) above the 1991-2020 average. Some individual days saw anomalies exceeding 12 degrees Celsius (21.6 degrees Fahrenheit) above normal. Southern and western Europe were hardest hit, though typically cooler northern regions, including the UK, also experienced thousands of heat-related deaths. Almost one-third of all deaths occurred during a particularly intense two-week period from June 17 to July 1, when mean temperatures were more than 5 degrees Celsius above the 1991-2020 average.
To estimate the death toll, researchers compared actual summer temperatures in the 854 cities with temperatures modeled for a world without human-caused climate change. They then applied peer-reviewed research on the relationship between high temperatures and daily mortality to calculate excess deaths. The methodology has been validated by comparing model estimates to official mortality statistics where available. For example, researchers estimated 2,700 heat-related deaths in England and Wales during May and June; the UK Health Security Agency later identified approximately 2,880 deaths in that period.
The highest death rates occurred among people aged 85 and older, though heat affected all age groups. More than 800 people between ages 20 and 44 died from heat-related causes. The researchers noted that official death certificates often do not list heat as a cause of death even when extreme temperatures are a significant factor, making heat deaths inherently difficult to measure and potentially underreported.
The role of climate change in European heat deaths has grown substantially over time. In the early 2000s, fossil fuel pollution was responsible for approximately 40 to 45 percent of heat deaths; by 2026, that proportion has risen to roughly two-thirds. Clair Barnes, an extreme weather and climate change researcher at Imperial College London and lead author of the research, stated: "The summer of 2026 is likely to have been the worst on record for heat-related mortality across much of Europe." She emphasized that Europe is the fastest-warming continent and that much of the region's infrastructure was not designed to withstand the temperatures now occurring due to human-caused warming.
The studies' release comes weeks before international climate negotiations in Turkey and days after a UN report indicated that the world has already lost its chance to limit global warming to 1.5 degrees Celsius above pre-industrial levels. Researchers and public health experts have noted that most heat deaths are preventable with adequate preparation, including access to cooling spaces, air conditioning, shade, and public health interventions targeting vulnerable populations.
