Past the 40 ° C bar, the thermometer panics in the southwest

Past the 40 ° C bar, the thermometer panics in the southwest

Past the 40 ° C bar, the thermometer panics in the southwest

This Monday, 40 ° C was exceeded in mid-afternoon, in Bégaar in the Landes. It was 40.1 ° C, Météo France noted, which is a new record for the month of September, for this city in the south of the department. “We also recorded 39.6 ° C in Orthez (Pyrénées Atlantiques), where the record dates back to 14 September 2020 with 37.9 ° C, and 38.9 ° C in Pau, against 36.3 ° C on 7 September 1970 ”continues Francis Morisset, meteorologist and departmental climatologist for Météo-France in Biarritz.

Dozens of temperature records for the month of September have in fact been broken across the southwestern district. It was 39.1 ° C in Mont-de-Marsan, 39 ° C in Dax, 38.1 ° C in Sauternes south of Bordeaux, 37.2 ° C in Tarbes (Hautes Pyrenees) and even 35.1 ° C at Nantes (Loire-Atlantique) …

However, the all-time record for a month of September was not broken. “It dates back to 7 September 2016, when it was 40.5 ° C in Cambo-les-Bains (Atlantic Pyrenees), observes the meteorologist from Météo France. On 7 September 1966 we also had 40.2 ° C in Arjuzanx and 40 ° C in Parentis (Landes). We can also note 39.8 ° C on 14 September 1962 in Saint-André-de-Seignanx and 37 ° C in Bordeaux on 17 September 1967. “The average maximum temperatures of September in New Aquitaine, rather gravitate between 23 ° C and 25 ° C.

A heat spike that occurs after three heat waves

Francis Morisset believes, however, that “we shouldn’t get into the orange heatwave vigilance, because the phenomenon won’t last long enough. This is why we speak of heat spike. But it comes after three heat waves since June. It should also be noted that on Monday 40 ° C was exceeded… for the fourth consecutive month.

This heat spike runs through the southwest on Monday, “despite more cloud cover than on Sunday,” the forecaster also points out. “This is due to the instabilities coming from the Bay of Biscay which will give rise to high clouds. We are currently suffering from a depression, the former cyclone Danielle saw off the Azores a few days ago. This air, crossing the Pyrenees, undergoes a foehn effect, that is, the air mass compresses, which heats and dries it. We had the same situation, more or less, during the June heatwave, with a depression located off the coast of Portugal that brought in a flow from the south, bringing in air from North Africa. It is also possible that the air mass becomes increasingly sandy, as in June. “

Beware of storms at high altitudes

From Tuesday, however, temperatures should begin to drop, «even if they will still remain above 30 ° C. »« The problem is knowing if we will have rain, because thunderstorms await us at high altitudes. These are located at about 4,000 meters and precipitation evaporates from 3,000 meters, with the risk of lightning. This situation can therefore create sparks, with a wind that could attract the embers, so beware of the risk of fire, especially in the Landes and Gironde where the ground is still very dry. “

A new heat spike “is likely to reappear next week” warns the forecaster, “with temperatures still lower, but which will still remain above seasonal norms. “

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