Since midday, 72 French departments will be affected by a red heatwave alert. With 50 million French people affected, this Thursday, June 25 could mark the peak of the heatwave that France has been experiencing since the start of the week. Once again, temperatures are expected to rise to “exceptionally high” levels, after reaching up to 43.8°C in Palluau (Vendée) on Wednesday, Météo France warns. Before beginning a gradual and uneven fall over the territory starting next night.
“On Friday, a gradual drop in temperatures along the Atlantic coast is taking shape following the stormy deterioration on Thursday evening,” indicates Météo France. First expected for Wednesday, then Thursday, the outcome of this episode of exceptional heat finally seems to be taking shape from this Friday.
It is the north-west of the country which will benefit first from slightly cooler air, which will arrive via the English Channel and the Atlantic, indicates La Chaîne Météo. Brittany, Normandy and the Pays de la Loire should benefit from more bearable weather from Friday. The rest of the Atlantic coast will have to wait until Saturday, when the storms increase.
For the rest of the territory, the horizon seems to recede the closer we think we are getting. The central regions and Île-de-France will have to wait until Saturday evening to feel a more significant drop, as the stormy deterioration passes. But moving back towards the west, the heat will probably persist for a few more days in the center-east, the Rhône valley but also the interior of the south-east. In eastern France, temperature records could be broken during the day on Saturday, particularly in Strasbourg where up to 40°C is expected.
It is on the Mediterranean rim that the decline will be slowest. The Weather Channel reports that in Provence, “the mistral could even maintain a dry and marked heat at the start of next week, with another 35 to 38°C possible in the interior.” In Marseille, extreme temperatures could persist until Wednesday July 1.
A stormy exit from the crisis
The end of the heatwave will therefore take place slowly, and in contrasting ways. The stormy episodes that will accompany it could also be locally violent. Météo France has already placed 12 departments on orange alert for storms, notably Côtes-d’Armor, Manche, Landes and Gironde, all of which are affected by red heat wave alert.
While temperatures will decrease starting this weekend, they will not immediately return to seasonal levels nationwide. The national thermal indicator – the average of 30 weather stations distributed evenly across the territory – which reached 30°C for the first time on Wednesday June 24, will probably not drop below 25°C before Monday.
According to this climatological benchmark, a national heat wave is characterized when this indicator reaches at least 25.3°C one day and remains above 23.4°C for at least three days. It ends when it falls below 23.4°C on two consecutive days, or below 22.4°C in one day.
If the end of this heatwave is approaching, the Minister of Ecological Transition, Monique Barbut, does not rule out a return of extreme heat soon. On Wednesday, on France Inter, she indicated that France would experience a “relative break” in the heatwave next week, but affirmed that “Météo France tells us that there is a high probability that, from the following week, we will return to extreme heat”. A “probability” which is however not a certainty.
