May Heatwave in Spain: Temperature Record and Rare Atmospheric Anomaly. Spain is experiencing an unusual May heatwave, with temperatures exceeding the norm by 5–10 degrees. The cause is a powerful atmospheric system trapping warmth and leading to unseasonably warm nights.
In mid-May, Spain is experiencing abnormal heat, which in both intensity and duration resembles the height of summer. According to Aemet, temperatures in several regions exceed seasonal norms by 5–10 degrees, and in the northern part of the country — by more than 10 degrees. In some cities, daytime temperatures rise above 34 degrees, and nighttime lows do not drop below 20, leading to so-called "tropical nights."
The main cause of such unusual May weather is a powerful atmospheric "lid" (drossal) that has formed over Western Europe. This high-pressure system stabilizes the atmosphere, virtually eliminating winds and vertical airflows. As a result, solar radiation, which already peaks in May, actively heats the ground surface, and the warmth is trapped in the lower layers of the atmosphere. This mechanism prevents temperatures from falling even at night, which is especially noticeable in large cities and inland areas.
The situation is aggravated by a phenomenon known as "subsidence"—the sinking of air masses from altitude to the surface. In the process, the air is further heated, which raises overall temperatures even more. According to meteorologists, in the current episode, subsidence is especially pronounced, amplifying the heat and making the weather situation in Spain unique for this time of year.
Experts note that such heat waves outside the summer season are becoming increasingly frequent and intense. This is linked to the general trend of climate change, which is shifting familiar weather boundaries. According to an Aemet representative, the current atmospheric scenario fully fits the recent years’ trend toward more frequent extreme temperatures in spring and autumn.
In the coming days, meteorologists do not expect significant relief: the heat will persist, rainfall will be rare, and the air will remain dry. Only on the Cantabrian coast by the end of the week is a slight drop in temperature possible, but in other regions of Spain no changes are expected. In the mountainous areas of the north and east of the peninsula, isolated thunderstorms are possible; however, they will not affect the overall picture.
Against the backdrop of this weather episode, it is worth recalling that in mid-May, Spain also faced forecasts of unstable weather and thunderstorms, especially in the northern and eastern regions. More details about recent forecasts and precipitation risks can be found in the article on the sharp deterioration of weather conditions in the middle of the month.
For reference: May temperatures in Spain usually range from 20–25 degrees during the day and 10–15 at night. The appearance of tropical nights and daytime highs above 34 degrees at this time of year is considered rare. According to the World Meteorological Organization, such weather anomalies may indicate accelerating climate change in the region.
