Heat dome turns May into August in Spain: temperatures near 40C

By Jesús Maturana Published on 28/05/2026 - 9:18 GMT+2•Updated 10:33 Share Comments Share Facebook Twitter Flipboard Send Reddit Linkedin Messenger Telegram VK Bluesky Threads Whatsapp

An anticyclonic ridge from North Africa traps hot air over western Europe. Badajoz hits 38 ºC, Santander keeps breaking records, France counts deaths. This is no blip but the new normal.

May began on a cool note. During its first few weeks, temperatures in Spain were below normal across almost the whole country. Nothing hinted at what was to come next. Since 19 May, however, thermometers have risen steadily, reaching values that would normally correspond to the height of summer.

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The culprit is a high-pressure system 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: this anticyclone acts like a lid that prevents the renewal of air, forces it to descend and, as it is compressed, heats it even further. The result is a stifling atmosphere that does not let up for days and that, in some places, represents an anomaly of up to 15 °C above the usual values for this time of year. In other words, the heat that would normally be expected in July or August has arrived two months early.

AEMET has recalled that at Santander Airport, with data going 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 records, temperatures of more than 38 °C have been recorded in May for the first time in the entire historical series.

The anomaly pays no heed to 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 is hottest 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 recording highs of between 37 and 39 °C for days, and in some parts of the south temperatures could brush 40 °C during the second half of the week. Badajoz, Seville, Córdoba, Jaén, Toledo and Zaragoza are among the hardest-hit provinces.

The Ebro valley, which has a history of being one of the peninsula’s great furnaces, is living up to its reputation again. But the most striking aspect of this episode is what is happening in the north. Bilbao is approaching the highest temperatures ever recorded there in May. Cantabria, Asturias and inland Galicia are also at levels well outside the norm.

Forecasts for the rest of the week point to a slight moderation in the far north-west, but an intensification towards the east: on Friday temperatures could reach 36 °C in Madrid, 38 °C in Seville and up to 39 °C in Lleida and Zaragoza. Any respite, if it comes, will not arrive before the weekend. That is how Spain will bid farewell to May and welcome June.

One factor that experts repeatedly emphasise is tropical nights, when the thermometer does not fall below 20 °C. In provinces such as Cádiz, Seville or Barcelona, the minimum temperatures will hover around or exceed that threshold for several consecutive nights.

The problem is not just the muggy conditions: when the body does not manage to recover during sleep, heat stress builds up day after day. Doctors warn that it is precisely these nights without relief, more than daytime peaks, that have the greatest impact on public health, especially among older people and those with chronic illnesses.

Europe on alert: records and first victims

The episode has no borders. In the United Kingdom, where such temperatures are much more exceptional than in southern Europe, temperatures reached 34.8 °C in Kew Gardens in London, surpassing 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 strung together several days with tropical nights, something virtually unprecedented for the 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 on orange alert, something unprecedented for May. In France two people have died while playing sport, one on Sunday in Paris and another on Monday in Lyon. Italy is also seeing record May temperatures.

The week of 25 to 31 May 2026 could go down in Europe’s climate history for the exceptionally high values reached, which go far beyond even the high values typical of summer. Meteorologists warn that temperatures are soaring between 12 °C and 16 °C above long-term climatological norms, as greenhouse gases continue to heat the planet.

The question many people are asking is whether episodes like this used to be normal. 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 become visible in May. What used to be brief incursions of spring heat is gradually becoming the new starting point.

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