Europe saw its first unusual summer heat in May 2026 when a heat dome produced temperatures that set records in several countries. By mid‑August, the region experienced its fifth heat wave of the season, with temperatures exceeding 40 °C (104 °F) over a broad area and remaining high overnight. Hospitals reported increased admissions for heat‑related illnesses, and heat‑related deaths were preliminarily estimated at 10,000 excess cases across the United Kingdom, France, Germany and Belgium. High temperatures caused buckling of highways and railway tracks, leading to road closures and transport disruptions, while large wildfires ignited in regions where they were previously uncommon. The heat intensified an ongoing drought, reducing river water levels and affecting water, power and agricultural supplies. The animation of daily maximum surface air temperature from May 1 to August 19, 2026, was created by NASA’s GEOS model combined with satellite observations; areas with temperatures at or above 40 °C are shown in dark red, according to the UK Met Office. Record temperatures were set at multiple locations: London reached 35.1 °C on May 26, breaking the previous May record by 2.3 °C, according to the UK Met Office; Bordeaux recorded 42.5 °C on June 24, surpassing its June record on three consecutive days, according to Météo‑France; Slovakian authorities recorded new national daytime and nighttime highs in August, according to local meteorological services. Combined June and July temperatures in Western Europe were the highest on record, according to the Copernicus climate monitoring service. European cities face heightened risk due to limited air‑conditioning penetration—about 23 % of homes have air‑conditioning compared with 90 % in the United States—and reduced green space, factors that contributed to higher heat‑related mortality, according to an analysis by the World Health Organization and researchers at New York University. Researchers have linked heat stress to the world’s leading cause of weather‑related deaths, with approximately 489,000 deaths annually, 36 % of which occur in Europe, according to WHO data. Deborah Carr, a sociologist at Boston University, noted that nighttime temperatures as low as 26.7 °C (80 °F) can be dangerous for older adults lacking air‑conditioning, and that Southern Europe, with an aging population, faces growing exposure, according to a study that used NASA demographic and climate data. In a study published in Lancet Planetary Health, researcher Qinqin Kong and colleagues modeled future heat exposure for different age groups, concluding that many regions will exceed human heat tolerance thresholds frequently, particularly affecting older adults, according to the paper. Kong, a recipient of a NASA Earth and Space Science and Technology award, said that understanding where and when heat limits are exceeded is critical for developing targeted heat action plans, emergency preparedness measures and health system responses. The findings aim to guide policymakers in designing heat mitigation strategies as extreme temperature events are expected to become more frequent.