Let’s stay with a figure: 34.3. It is, almost certainly, the most important data of the week. On Thursday, May 21, 2026, the thermometers of the city of Oviedo They recorded a temperature of 34.3 degrees. 1.8 ºC more than the highest temperature ever recorded in May in the capital of the Principality.
AEMET is convinced that between today and the weekend will be reached again (or even exceeded) this temperature. And yet, this is only a tiny part of the story.
Because the real story is that, in a region structurally protected by its oceanic climate, records are being broken in ways we would not have been able to imagine. And that’s without the country being in a ‘heat wave’.
What is happening? Although There is some controversy with the namewhat is happening is called ‘heat dome‘. That is, a subtropical anticyclonic ridge, anomalously powerful for this time of year, which is trapping very warm air above our heads.
Europe is bearing the brunt, it is true. Countries such as France, Germany, the Netherlands and the British Isles they are seeing temperatures between 10 and 15 degrees above normal. If everything goes as predicted by the models, the May records of half of Europe are going to explode on the 25th of this month.
And, of course, we are noticing that. As the haze falls on the Canary Islands (right at the eastern vertex of the dome), a good part of the country will suffer considerable heat. We talk about more than 34 degrees in Asturias and the Basque Country and 38 in the Guadiana valleys.
The Guadalquivir valley is already above 35.
And, as I say, all this without heat waves. Despite the magnitude of the episode, AEMET does not rate it like a heat wave in peninsular Spain. It is not. We already know that the operational definition requires exceeding the 95th percentile of daily maximum temperatures for the July-August quarter for at least three days and, of course, we are not going to go to that extreme.
What does all this heat tell us? Let’s be honest. For Andújar or Badajoz to reach 38 degrees on May 21 is rare, but not exceptional. But for Oviedo to reach 34.3 is a very different thing. It shows, above all, that the Cantabrian coast is beginning to stop being a “climate refuge.”
Why is all this important? In addition to an underlying climate issue, this warm episode is important because it is dangerous. The first extreme heat of the year is the deadliest because the population has not gone through the period of physiological acclimatization produced by progressive exposure to summer heat.
That is, because it is May and the Iberian summer has truly begun.
Image | Tropical TidBits
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