It was hot on Wednesday March 29 in the south-west of France. Several heat levels were even exceeded. Temperatures locally higher by 10 to 12 degrees than normal for the season were recorded, announced Météo-France. This summer mildness at the very beginning of spring, which also affected a large part of the territory to lesser degrees, should however only be ephemeral, a colder front being expected from the weekend on France.
Wednesday afternoon, it was more than 30 ° C in Dax (Landes) and Orthez (Pyrénées-Atlantiques), with 30.1 ° C. “This is the first time that we have reached this threshold on the metropolitan territory this year”explained to Agence France-Presse (AFP) forecaster Patrick Galois.
This threshold of 30°C is very rare in mainland France in March. It has so far only been exceeded twice: in Pau, on March 25, 1955 (31°C); and in Figari (Corse-du-Sud), on March 24, 2001 (30.3°C). The previous highest temperature recorded in March in Dax dated from March 21, 1990, with 29.9 ° C. That of Orthez dated March 31, 2021 (29 ° C).
Several unprecedented temperatures
Other cities also experienced unprecedented heat for the month of March, such as Mont-de-Marsan: 29.9°C, against 29.2°C; Clarac (Haute-Garonne): 27.5°C, against 26.5°C; Villefranche-de-Rouergue (Aveyron): 26.2°C, against 26°C; or even Belvès (Dordogne): 26.6°C, against 26.3°C.
In the rest of the country, temperatures were locally 6 to 8 degrees higher than normal for the season in several places, for example in Clermont-Ferrand with 25°C, in Nevers with 23°C, and in Paris with 21°C. , 10 more than Tuesday.
The phenomenon had started in the early hours of the day in Biarritz, which recorded its mildest night, with an average of 18.9 ° C, higher than the highest temperature recorded for the same month, March 4, 1998 , where the thermometer had reached 18.2°C.
This mildness is due to an Atlantic depression which, slowed down by an anticyclone in place over France, brought up a mass of very mild air over the country, in southerly currents. It is also fed by a foehn effect – the sudden heating of an air mass after it has crossed a mountain range – at the foot of the western Pyrenees.
However, this will not last, warns Météo-France. On Thursday, the high pressures will gradually fade to the east and a deterioration is expected for the weekend, with the shift to a westerly flow, which will bring showers on Friday.
“Temperatures will start to drop sharply, returning to seasonal averages on Friday, and this weekend we will even drop below normal for the start of April”said Mr. Galois.