Confirm that the summer of 2025 is the warmest since there are records is not enough. You have to understand why. And you have to do it fast

Astronomical summer is not over yet and it seems that the weather coincides with this, although we have already entered the month of September. However, experts from the State Meteorology Agency (AEMET) have already taken stock of the summer quarter of this year. We knew that this summer had been warm, but now we know that it has been the warmest.

Since we have records. The summer of 2025 has been the warmest of the historical series in Spain (in 1961), according to has released recently Aemet. In peninsular Spain, the quarter between June and August has left us a thermal anomaly of 2.1º Celsius, taking as reference the period between 1991 and 2020.

This year’s has also been a very warm summer on the islands: 1.5º above what would be common in Balearic Islands and 0.9º more in the Canary Islands.

In the Peninsula, “excess heat” has been distributed quite homogeneously, although in important areas of the territory of communities such as Galicia, Castilla-La Mancha, and Castilla and anomalies of more than 2.5º were seen. According to Explain Aemetit was precisely in Galicia and the two plateaus where anomalies of more than 3º are observed.

Overcoming the record. The warmest summer until now had been the 2022. The new record exceeds the marking during that summer in just 0.1 and supposes the fourth consecutive year in which positive anomalies are recorded during the summer, always taking as reference the period between 1991 and 2020.

June, the most anomalous month. A good part of the situation is due to the heat that We live in the month of June. The first month of this summer was not only the warmest June since there are records, it was also the 30 days with the greatest warm anomaly of which we have record: 3.6º Celsius.

During that month the heat was especially concentrated in the east of the country, with a small area between Aragon and Catalunya exceeding 4.5º of thermal anomaly.

What happened this summer? Summer was marked by a low atmospheric circulation, with anticyclonic conditions that allowed the intrusion of African heat in almost all of the peninsula. According to Aemet, this summer we saw three waves of heat, two that affected Peninsula and Balearic Islands, and another that reached the Canary Islands.

The peninsular affected 40 provinces and lasted for 17 days, from June 18 to July 4. The Second heat wave It was still more intensegenerating an anomaly of 4.2º; It affected 42 provinces and lasted for 16 days, between August 3 and 18.

Both heat waves were among the longest we have registered and turned 2025 in the second year with more days with active heat waves (33) after 2022 (41 days).

And what about the rains? In addition to warm, summer this year has been dry, at least in peninsular Spain. They saw each other on average 57 mm of rain In the area, 81% of what would be common on these dates. The southwest quadrant was the most affected by the lack of rains, although rainfall was rather scarce in most of the country, except for some areas of the Ebro basin, center of the northern plateau, and some areas of the Mediterranean basin.

The situation was unequal in the Balearic Islands, with the western part of the archipelago seeing few rainfall and the eastern area watching a more humid summer. Even more irregular what was seen in the Canary Islands, where together there was a wet summer (133% of the average rainfall for summer), but with very concentrated rainfall in specific areas.

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Image | ECMWF / Victor of Dompablo