Just weeks after a severe heatwave that broke all-time May records, Europe is experiencing another major heatwave that is breaking June and annual records. This is particularly remarkable given that June is not historically the hottest month in Western Europe. Across France, Germany, Italy, Spain, and southern England, temperatures are reaching 5–12°C above seasonal averages, driven by a persistent high-pressure system. This pattern has transported hot air from North Africa into the region while also bringing clear skies and strong sunshine, which have further intensified the heat.

Heatwaves pose a serious threat to human health and have profound impacts on ecosystems. During the summer of 2022, more than 60,000 people across Europe died as a result of extreme heat. Even in the following summer, which was significantly cooler, over 47,000 heat-related deaths were recorded (Gallo et al., 2024). Last year, the first heatwave in Europe, also hitting at the end of June, cost an estimated 2,300 people their lives in only 12 European cities (Grantham Institute, 2025). 

In addition to the direct impact on mortality, extreme heat affects ecosystems, infrastructure services and daily life. The high temperatures are pushing cooling demand to its highest level in at least 45 years while significantly increasing wildfire risk, particularly in Spain and France (Straits Times, 2026). France has been among the hardest-hit countries, already reporting at least 40 fatalities, widespread school closures, cancelled outdoor events, and major rail disruptions as extreme heat leads to thermal expansion of tracks and disruption to overhead power lines (Guardian, 2026). Dry conditions are intensifying, with soil moisture approaching record seasonal lows and emergency medical calls rising by 20% (Joubioux, 2026; Peseckyte, 2026a; Reuters, 2026; Straits Times, 2026). In the UK, East Surrey Hospital declared a critical incident due to surging demand, restricting services to life-threatening emergencies only (Peseckyte, 2026b). Italy has experienced heat-related deaths, increased emergency-room admissions, and power outages linked to soaring air-conditioning use, while healthcare and transport systems in Belgium and the Netherlands have faced growing strain and service disruptions. In Belgium, wildlife rescue centres have also reported a sharp rise in heat-stressed animals, particularly young birds (Reuters, 2026). Meanwhile, Spain is confronting heightened drought and water-stress conditions as reservoir levels come under increasing pressure. The heatwave is also placing stress on European energy systems, with concerns over reduced output from French nuclear power plants cooled by the Rhône and Garonne rivers. As France forms a key part of the continent’s electricity network, generation restrictions could tighten regional power supplies and contribute to higher electricity prices and worsen Europe’s growing summer energy poverty (Straits Times, 2026; European Commission, n.d.).

Researchers from Sweden, Denmark, the United States, the Netherlands, Ireland and the United Kingdom collaborated to assess to what extent human-induced climate change altered the likelihood and intensity of the extreme heat in Western Europe. The analysis focuses on the 3 hottest days and nights over the most affected area (red outline, Figure 1), and additional analysis of the 19 capitals of the affected countries. 

Figure 1: The anomaly in the 7-day average for peak minimum and maximum daily temperature relative to a 1991-2020 June climatology.

Figure 2: the cities (EU + Switzerland + UK + Norway urban regions with a population of over 50,000) where WBGT records were broken (or forecast to be broken) during this heatwave. A record was broken in approximately 45% of urban regions.

• Heatwaves cause more deaths in Europe than all other natural hazards combined. As temperatures continue to rise, ageing populations, growing prevalence of chronic illness, and uneven access to cooling and heat-resilient housing are increasing vulnerability, placing mounting pressure on health systems. 
• Vulnerability to heat ranges across society from elderly people living alone to populations facing socioeconomic disadvantage and chronic illness, including homeless people and migrants, highlighting the need for adaptive, equity-focused heat-health policies.
• Over the region studied this heatwave is the most severe ever recorded. 
• In 1976, when some of the previous European records were set, the 2026 temperatures would have been virtually impossible to occur in June, while also highly unlikely at any time of the year. In 2003, the first major heatwave of this century, daytime heat like this would still have been very rare, about 10 times less likely than today, while nighttime temperatures such as this June would have been more than a hundred times less likely in 2003. 
• Across large parts of Western Europe, June is warming faster than any other month. In addition, daily maximum temperatures are warming faster than night time temperatures, though both are warming much faster than global warming. The hottest daily temperatures are warming at about triple the rate of global warming and night time temperatures at about twice the rate. Many capital cities are experiencing not only their hottest June 3-day period but also the hottest three-day period since 1950, according to the ERA5 dataset. However, due to global warming, these very high temperatures are now expected regularly during the summer months in many capitals. 
• This means that a similar heatwave in June would have been about 3.5°C cooler during the day in 1976 and about 2°C cooler in 2003. The nighttime temperatures would have been about 2.4°C cooler in June 1976 and about 1.3°C cooler in June 2003. 
• This June 2026 heatwave occurred under a circulation pattern broadly similar to historical analogues – Southerly Flow. However, a similar circulation pattern now produces significantly hotter temperatures than it did in the mid-20th century because the climate baseline has warmed.
• As the combination of heat and high humidity is especially dangerous for human health, we also analysed WBGT*. During this heatwave (18th – 29th June), 45% of European cities are breaking indoor-WBGT thresholds. 
• Heat risk is concentrated in cities, where urban heat island effects, ageing building stock, and socioeconomic inequalities combine to intensity exposure. Many homes, schools, transport systems, and energy infrastructure were not designed for prolonged extreme heat, highlighting the urgent need for equitable adaptation, building retrofits, passive cooling measures, and heat-resilient urban design. 
• This summer shows that at 1.4°C of global warming, extreme heat is already reaching the limits of our societies’ ability to cope. Our analysis here shows that intense heat is increasing rapidly even in living memory, with such events tens to hundreds of times more likely since only 2003 and virtually impossible just 50 years ago. A rapid phase-out of fossil fuels is critical if we are to avoid even higher temperatures and their consequences in the future.

*Wet Bulb Globe Temperature (WBGT)

To measure the combined effect of environmental factors on human heat stress, Wet Bulb Globe Temperature (WBGT) is used as a composite index, combining humidity, radiant heat (such as direct sunlight), and air movement, all of which affect the body’s ability to regulate its internal temperature through sweating and heat exchange. By capturing these interacting variables, WBGT provides a more physiologically relevant assessment of thermal strain, particularly during outdoor physical activity. Consequently, it is widely applied in fields such as sports science and occupational health (Grundstein et al., 2023).

In this study we approximate WBGT using temperature and humidity (per Zhang et al., 2024) – which means results apply best to a sheltered and shaded area, without the heating effect of direct sunlight or the cooling effect of wind.