Barcelona's official heatwave thresholds have increased for both daytime maximums and nighttime minimums, according to the Meteorological Service of Catalonia (Meteocat). This means higher temperatures are now needed to trigger warnings in the city.
To be classified as a heatwave in Barcelona, the maximum temperature must now reach 34.3 ºC for three consecutive days or more. This figure marks an increase of 0.2 ºC from last year and 0.7 ºC compared to six years ago. Meteocat calculates these thresholds based on the warmest 2% of maximum temperatures recorded in June, July, and August over the past 15 years.
Nighttime heat alerts in Barcelona will now require a minimum temperature of 27 ºC, a rise of 0.5 ºC from two summers ago. Coastal areas are particularly affected by these higher nighttime thresholds, making sleep difficult during intense heat periods.
Varying Heatwave Criteria Across Catalonia
While Barcelona's thresholds have risen, criteria vary significantly across Catalonia. In the Vallès region, for instance, 37 ºC is needed to declare a heatwave. Furthermore, 31 municipalities in Catalonia, primarily in Segrià (13) and Ribera d'Ebre (eight), require temperatures of 40 ºC or more for three days to meet the heatwave definition. Other affected areas include Noguera (four), Pallars Jussà (three), Priorat (one), Baix Ebre (one), and Osona (one).
Conversely, Setcases in Ripollès continues to have the lowest heatwave threshold in Catalonia, at 30.4 ºC. For nighttime heat, 20 municipalities, including all those in Barcelonès (with L'Hospitalet de Llobregat at 25.2 ºC), seven in Maresme, three in Baix Llobregat, two in Alt Empordà, and one each in Bages, Baix Penedès, and Ribera d'Ebre, now need minimums above 25 ºC for alerts. In contrast, Alp in Cerdanya has a much cooler summer minimum threshold of 15 ºC.
New Calculation Method for Thresholds
For the first time, Meteocat has used 15 years of data to establish these thresholds, extending from the previous 10-year period. This broader dataset has, in many cases across Catalonia, resulted in lower current thresholds compared to a year ago. However, Barcelona stands out as an exception, with both its daytime and nighttime temperature thresholds increasing.
