Heat dome turns May into August in Spain as temperatures near 40C
A North African anticyclone traps hot air over western Europe. Badajoz hits 38°C, a May record; Santander keeps breaking highs; France reports deaths. This is no blip but the new normal.
May started off cool. During its first weeks, temperatures in Spain were below normal across almost the whole country. Nothing foreshadowed what would come next. Since 19 May, however, thermometers have been climbing steadily, reaching values that would, under normal conditions, correspond to the height of summer.
The culprit is an area of high pressure stretching from North Africa to the British Isles, which meteorologists call an anticyclonic ridge or, in more popular terms, a heat dome.
The mechanism is simple: that anticyclone acts like a lid that prevents the air from being renewed, forces it to sink and, as it is compressed, heats it even further. The result is stifling conditions that drag on for days and that, in some places, represent an anomaly of up to 15°C above the usual values for this time of year. In other words: the kind of heat that would normally be expected in July or August has arrived two months early.
AEMET has recalled that at Santander Airport, where records go back to 1954, temperatures above 30°C had only been recorded before June on two days. This year there have already been six. At the Badajoz Airport observatory, with 71 years of data, temperatures have topped 38°C in May for the first time in the entire historical series.
The anomaly cuts across geography: the episode is hitting the south-west of the peninsula, the Cantabrian north, the Ebro valley and much of western Europe alike.
Where it bites hardest and what to expect in the coming days
Within Spain, the heat is unevenly distributed but there are few places spared. The south-western quadrant has been registering highs of between 37 and 39°C for days, and in some parts of the south the 40°C mark could be approached in the second half of the week. Badajoz, Seville, Córdoba, Jaén, Toledo and Zaragoza are among the hardest-hit provinces.
The Ebro valley, long known as one of the peninsula’s great furnaces, is living up to its reputation again. But the most striking feature of this episode is what is happening in the north. Bilbao is closing in on the highest temperatures ever recorded there in a month of May. Cantabria, Asturias and inland Galicia are also at levels well outside the norm.
Forecasts for the remainder of the week point to a slight easing in the far north-west, but an intensification further east: on Friday temperatures could reach 36°C in Madrid, 38°C in Seville and up to 39°C in Lleida and Zaragoza. Any let-up, if it comes, will not be before the weekend. That is how Spain will see out May and usher in June.
One factor that experts keep stressing is tropical nights, when the thermometer does not fall below 20°C. In provinces such as Cádiz, Seville or Barcelona, minimum temperatures will hover around or exceed that threshold for several nights in a row.
The problem is not just the muggy discomfort: when the body fails to recover during sleep, heat stress builds up day after day. Doctors warn that it is precisely those nights without respite, more than the daytime peaks, that have the greatest impact on public health, especially among older people and patients with chronic illnesses.
Europe on alert: records and first victims
The episode respects no borders. In the United Kingdom, where such temperatures are far more exceptional than in southern Europe, they reached 34.8°C at Kew Gardens in London, beating the previous May record of 32.8°C set in 1922 and equalled in 1944.
The following day the record was broken again with 35.1°C, and the country has endured several days of tropical nights in a row, something virtually unprecedented for this month.
France has seen the harshest side of the episode. The mercury reached 35°C near London and could climb to 39°C in some areas of France and Spain. The French authorities placed several departments in the west of the country under an orange alert, something never seen before in May. In France two people have died while exercising, one on Sunday in Paris and another on Monday in Lyon. In Italy, May temperature records are also being broken.
The week of 25 to 31 May 2026 could go down in Europe’s climate history for the extreme values reached, which go far beyond the already high figures typical of summer. Meteorologists warn that temperatures are soaring between 12°C and 16°C above the long-term climatological norms, as greenhouse gases continue to heat the planet.
The question many people are asking is whether episodes like this were normal in the past. The answer is nuanced. Spring heatwaves have always existed, but their intensity, extent and duration are now different.
Climate attribution studies estimate that June heatwaves in Europe are now around ten times more likely than under pre-industrial conditions, and the same trend is beginning to appear in May. What used to be brief incursions of spring warmth is gradually becoming the new starting point.
