The weather pattern in May 2025 closely mimics that of the previous year, 2024: a month that initially embraced cool breezes and showers, only to culminate in a blazing heatwave reminiscent of summer. This past Thursday, Spain experienced its first 40°C of the year, with Seville's airport observatory recording this rare event for only the third time ever in May since records began in 1951. Previously, such sweltering conditions were recorded only twice—in May 2015 and May 2022—marking the current episode as comparable to those rare occurrences.

The question arises: is reaching 40°C in May an anomaly or a regular occurrence, as some skeptics suggest? According to Rubén del Campo, spokesperson for the Spanish State Meteorological Agency (Aemet), "It's not entirely extraordinary, not unprecedented, but certainly unusual." These recent temperatures are 5°C to 10°C higher than usual, with some areas experiencing nearly 15°C above normal limits.

Data from Aemet's Climatological Database reveals that the first recorded instance of 40°C in May was in 2006, a relatively recent development. On May 17 of that year, Córdoba, Almadén, Andújar, and Linares were the initial locations to break this barrier, with Andújar reaching an astonishing 42.3°C. The following day, Murcia also hit 40°C.

Over the past 19 years, this marks the seventh occurrence of 40°C in May. Carcaixent in Valencia holds the record for the highest May temperature in Spain with 44.4°C in 2015. Surprisingly, most of these 40°C readings, totaling 71 entries across 15 provinces, were not in the expected hotspot of Seville but rather in Valencia. Murcia, Seville, Jaén, Las Palmas, and Alicante also saw significant numbers, with individual recordings in Almería, Badajoz, Barcelona, Castellón, Ciudad Real, Huelva, Málaga, and Gran Canaria. This May alone, three more entries have been added—two in Seville and one in Huelva—with potential for further records in the Guadalquivir region.

The bulk of these extreme temperatures cluster around just four notable heatwaves: in May of 2006, 2015, 2022, and 2024, with additional isolated instances in 2010 and 2012. The most severe was in May 2015, with temperatures exceeding 40°C on 50 occasions. May 2022 followed with ten such instances, while 2006 saw five, and 2024 recorded four.

Montoro in Córdoba leads with five occurrences, previously holding Spain's national heat record with 47.4°C until surpassed by La Rambla in August 2021. Valencia ranks second with four instances in May, followed by La Aldea de San Nicolás, Murcia, Andújar, and Córdoba, each with three.

The underlying cause of this alarming trend is unequivocal: global warming. Such off-season extreme temperatures are increasingly probable due to climate change. As the Aemet spokesperson emphasizes, it's notable that no records of 40°C or higher in May existed prior to 2006.