It is often said: “After the rain, the good weather. “But this week, it was rather:” After the heat wave, the freshness. Mercury is doing the splits in France. After experiencing its hottest day last week after August 15, France went through its coolest day of the summer on Tuesday with a national thermal indicator at 17.34 degrees, according to Météo-France.
With temperatures nationwide 2.56 degrees below normal for the season (period 1991-2020), “it is indeed the coolest day of the meteorological summer of 2023, ahead of August 7 and the August 28, “said Météo-France on Wednesday. Last Thursday, the national thermal indicator, which represents a daily average of the air temperature recorded in 30 weather stations representative of the territory, was 27.8 ° C, a record never reached after an August 15 since 1947.
Drops of 20°C locally
But since then, a northwesterly flow combined with a disturbance has caused temperatures to drop in France, with sometimes impressive local differences. In some regions, the fall in mercury has sometimes exceeded 20 degrees in just a few days, especially in Auvergne-Rhône-Alpes, where the snow has returned above 2,500 meters.
“The deviation from the seasonal averages went from +8 to +16°C last Thursday to -12°C to -4°C on Monday August 28” underlines the national forecaster. And on Tuesday, a city like Lyon lost more than 19 degrees in the space of 5 days, dropping from 41.4°C on Thursday to 22.3°C. The difference was even greater in Bourg-Saint-Maurice (Savoie), dropping from 37.5 ° C to 13 degrees, while Lons-le-Saunier (Jura) saw its temperatures almost halved, from 39 ° C to 19.8°C.
New values
Similarly, Embrun (Hautes-Alpes), after experiencing an unprecedented series of 16 consecutive days with a maximum above 32°C, found itself with a mercury of 14.4 degrees on Monday, its afternoon of August the coolest since the monthly low of August 20, 1977.
In the Hautes-Alpes, the departmental thermal indicator was 23 degrees, an unprecedented value for all months combined, and it fell to 7 ° C on August 28. “Since the existence of the departmental indicator in 1947, only three days in August have been cooler [en 1986, en 1963, et en 1948] “, underlines Météo-France.