If you still have a few days of vacation left, try spending them in Brittany or on the Channel coast. Because elsewhere in France – and more particularly to the south of a line running from the Gironde estuary to Alsace – the most intense heatwave episode of the summer is looming with the arrival of a heat dome, in other words “a vast anticyclonic zone at all levels of the atmosphere” which, somewhat like a bicycle pump, “traps the already hot air and warms it further by compression” .
The temperature will increase over the weekend to reach a peak in intensity early next week, Monday or more likely Tuesday. Twelve new departments switch to heat wave orange vigilance this Friday, in addition to the seven who were already suffocating.
What temperatures to expect?
This Thursday, the mercury has already reached 33 to 36 ° C in the plains of the Southwest, 34 to 37 ° C in the interior of Provence and temperatures have remained “reasonably” below 30 ° C in the North . “But on Friday, the heat will rise further north and will increase significantly in the south, explains Christelle Robert, forecaster at Meteo France. We expect in the South-West, but also in the Rhone Valley and Provence, values of 34/37°C, locally 38°C”. Alsace should also suffocate. On Saturday, an additional notch will be taken in Provence with peaks expected at 39°C.
Everything will go to a crescendo on Sunday, when the heat will again push its horn towards the north and northeast and trigger a real furnace in the South: 40°C in the shade could be reached both in the South- West, in Languedoc-Roussillon and in the south of Provence with possible peaks at 41°C. “The peak of this episode is expected between Monday and Wednesday”, specifies the specialist, who expects a refreshing stormy deterioration on Thursday, yet to be confirmed.
Is it exceptional?
The heat wave in the middle of August, nothing new under the sun will say the most pragmatic. And yet, such an intense episode is not so frequent after August 15th. “Since 1947, there have been 46 heat waves observed, so 10 started during the month of August and among them six after August 15”, indicates Lauriane Batté, climatologist at Météo-France. These six late episodes all took place in the 21st century. In 2001, 2009, 2011, 2012, 2016 and 2017. But the trend does not surprise scientists at all in the context of global warming with models that predict that the number of summer heat waves could increase ninefold by here 2100.
The 2012 record could fall
The standard thermometer used in France is the “national thermal indicator”, an average of the temperatures in 30 representative stations distributed throughout the territory. It reached its maximum after August 15, i.e. 26.4°C on August 19, 2012. “According to the latest forecasts, the indicator could reach more than 27°C during the day on Tuesday, which would constitute an unprecedented heat value for a meteorological end of summer”, emphasizes Météo-France. Roll on next Thursday.