Paris, 25 May 2026
A powerful heat dome has settled over western Europe, pushing temperatures to record May highs across the United Kingdom, France, Italy and Spain and prompting authorities to issue health warnings and restrict outdoor work.
The UK Met Office said Monday was the hottest May day on record, with the mercury hitting 33.5°C at Heathrow near London by early afternoon — more than a degree above the previous benchmark set in 1922 and 1944. "The weather here, it's like a mini version of hell. It's like really hot," said 10-year-old visitor Liza Nizari.
In France, eight western departments were placed under an orange heatwave alert (vigilance orange canicule) by Météo-France from midnight Monday, including Finistère, Morbihan, Ille-et-Vilaine, Maine-et-Loire, Mayenne, Vendée and Loire-Atlantique. That represents an escalation from the yellow alert that had been in place since Sunday.
The agency warned that the heatwave — unusual for the season — would intensify on Tuesday, bringing temperatures of 32°C to 35°C across much of Brittany and peaks of up to 37°C in southern areas. Twenty other departments, from the western half of the country to Paris, the Rhône and Isère, remain under yellow alert.
France Activates Unprecedented Early Alert
Météo-France stated: "La vague de chaleur inhabituelle pour la saison que connaît la France va se renforcer mardi 25 mai, avec le début d'un 'épisode caniculaire' inédit pour un mois de mai dans l'ouest du pays." The agency defines a full-blown heatwave as intense heat lasting at least three consecutive days and nights, posing a health risk to the entire exposed population.
"C'est la première fois que ce dispositif d'alerte, qui analyse à la fois les conditions météorologiques et le risque sanitaire, est activé si tôt dans l'année," Météo-France added, underlining the exceptional nature of the May event. Dozens of monthly temperature records were broken again on Monday: Bergerac hit 34.7°C, Brest 33°C, Rennes 32.4°C, Nantes 34.3°C, and Angers 34°C — surpassing a record that had stood since May 1947.
The heat is being fuelled by a "heat dome", a zone of high pressure that traps hot air coming from North Africa. This anticyclonic configuration has consolidated over the Mediterranean, bringing summer-like conditions across much of Central Europe and forecast to push the peak into Wednesday.
Heat Dome Fuels Coast-to-Coast Records
In Italy, the heat is set to intensify midweek. Forecasts for Wednesday 27 May project maximum temperatures of 34–35°C in the Po Valley and inland central areas such as Tuscany and Umbria, with even higher values in large urban centres. Night-time temperatures are also expected to stay unusually high, with the first 'tropical nights' — defined as nights when the minimum does not drop below 20°C — likely in parts of the Po Valley and central Italy.
Spain is bracing for temperatures to peak later in the week at around 38°C (100°F). The combination of extreme heat and stagnant air is worsening air quality: a parallel ozone pollution episode prompted the French air quality monitoring laboratory LCSQA to warn of exceedances of the information threshold across the Île-de-France and the Rhône valley on Tuesday.
Ozone Pollution Compounds Health Risks
Ozone concentrations are forecast to surpass 180 microgrammes per cubic metre per hour, which can trigger respiratory and cardiovascular discomfort, especially among vulnerable groups such as the elderly, pregnant women, infants and young children, Airparif said in a statement. In the Rhône area, the prefect activated an orange pollution alert, cutting speed limits to 70 km/h on certain roads, banning waste burning and restricting solid-fuel barbecues.
French Prime Minister Sébastien Lecornu is to chair an inter-ministerial meeting on the heatwave on Thursday "pour faire le point sur la préparation des services de l'État" in the face of this exceptional episode, his office announced.
Londoner Lindy Brand-Daloze, 66, summed up the sentiment on the streets: "It's warm, but it's climate change, isn't it? So, you know, [we have] probably got to get used to this." From Thursday 28 May onwards, some relief may appear as high pressure weakens and allows a return of thunderstorms, especially over mountainous areas.