Weather: “These temperatures do not correspond to seasonal norms…” Will the heat wave in France last?

After the passage of the Caetano depression over mainland France, which caused snowfall in the north and stormy winds in the south between Thursday 21 and Friday 22 November 2024, minimum temperature records were recorded during the night from Saturday to Sunday. If the alternation between hot and cold periods is common, such high nighttime temperatures are unprecedented for the season, and result from global warming, according to Frédéric Nathan, forecaster at Météo France.

Temperature records

Sunday afternoon, an average of 17°C was recorded in the northern half. During the night from Sunday to Monday, minimum temperature records were reached, with 26 degrees in Pau (Pyrénées-Atlantiques), 15.1°C in Campistrous (Hautes-Pyrénées) and 15.5°C in Lorient (Brittany). This Monday morning, it was more than 20°C in the Pyrenean valleys, just a few days after the first morning frosts. Values ​​worthy of a month of June, according to Christophe Dedieu, meteorologist at Météo Pyrénées: “It is a foehn effect, which dries out and raises temperatures, but also a summer air mass coming from the south , with values ​​of 14 to 16 degrees in the free atmosphere, around 1,500 meters.” Furthermore, “a depression circulating over Brittany carries winds to the south to southwest territories capable of warming the air mass”, notes Frédéric Nathan, forecaster at Météo France.

“This is not a return to seasonal normals”

The current temperatures, comparable to those of the spring season, are not usual, according to Frédéric Nathan. “The climate obeys natural variability with an alternation between hot and cold periods,” he explains. “Except that little by little, with global warming, the thermometer is rising. The temperatures recorded since Saturday do not correspond to a return to seasonal norms. We should not have such high temperatures in November. In Toulouse alone, every year, we break temperature records.”

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Temperature drops to be expected

However, temperatures should return to seasonal norms within two to three days. “Behind this disturbance, which warms the air, is colder air, which corresponds to the November averages,” notes Frédéric Nathan. “The mild spell is already coming to an end. We can expect averages of nine degrees in the northern half and 13 degrees in the southern half between now and Friday.”

As for the strong winds, linked to the “Bert” depression, they persist this Monday afternoon in the south-eastern half of the country, but are easing ahead of the rainy front which is progressing from the west. Only the Loire and the Rhône are still on orange “wind” alert.