Spain has activated its first-ever red heat alert for the month of September, as temperatures pushed past 45C in parts of the south1. A red alert is the highest level in Spain's heat-warning system, run by AEMET, the country's national weather service.
The mercury hit 45.7C in El Granado, a town in Huelva province in southwestern Spain, on Thursday1. That reading tied Spain's national record for the hottest September day, a mark previously set in Montoro back in 20169.
Where the red heat alert hit
AEMET raised its warning to red for the Morena y Condado area in Jaén province, where highs of up to 44 degrees were expected3,5. The agency also upgraded its warning for Sevilla province to red, the highest possible level, as temperatures there reached 45.1C.
Officials described the alert as unprecedented for Andalucia at this point in the year. Spain's national broadcaster reported that AEMET briefly issued the top red alert in small areas of Andalusia, the first time such a warning had gone out in September since the alert system began in 200710.
What drove the extreme heat
A heat dome settled over Spain and the Balearic Islands, driving the spike in temperatures2. A heat dome forms when a persistent area of high pressure traps air beneath it, causing that air to sink and heat up like a lid holding the warmth in place2.
Thursday and Friday marked the peak of the event, with highs likely to reach 42 to 43 degrees across the south of the mainland and pass 40 degrees elsewhere2. The pattern brought temperatures more typical of the height of summer than of early September2.
Eleven of Spain's autonomous communities were placed under heat warnings, with Andalucia, Castilla-La Mancha and Extremadura reaching the orange level, one step below red4.
Highs of up to 42 degrees were forecast for the Morena y Condado area and the Guadalquivir valley in Jaén province, and also in the Córdoba and Sevilla countryside, where orange-level warnings kicked in4.
A record that matters beyond one week
Spain registered its joint-highest temperature for September on record on Thursday, September 3rd, with 45.7C measured in a town in the southwest11. AEMET reported the milestone the following day11.
The extreme heat arrived alongside a stark seasonal outlook. AEMET forecast that Spain would be clearly hotter than usual in September7.
For an agency to call an entire month's outlook clearly above normal is a strong signal, not a routine forecast caveat7. Combined with a record-tying 45.7C reading and a red alert that had never before been triggered in September, it points to a heat pattern arriving earlier and lasting longer than the historical norm for the region1,7,10.
Anyone in the affected provinces should follow official AEMET guidance during active red and orange alerts, including limiting outdoor activity during peak afternoon heat. Check the forecast for your city to see current conditions and warnings near you.