While a fifth heatwave is a strong possibility – forecasters predict yet another hot spell starting on Tuesday, August 23th – the autumn storm season in the far south of the country is a longer-term weather concern for meteorologists as climate change exacerbates annual weather events.
Violent and sometimes deadly storms – known as épisodes cévenol or épisodes méditerranéen – are not unusual in the south of France in the autumn.
In November and then again in December 2019, Cannes and its surroundings were partially inundated. Four years earlier, on the night of October 3rd and 4th, 2015, an épisode méditerranéen in an area stretching from Mandelieu to Antibes left 20 dead.
The storms have happened annually for centuries – caused by warm air currents coming off the Mediterranean meeting colder air in the mountains and Massif Central as the season changes.
The storms may be relatively common – up to 10 such storms at the end of a summer in France are classified as épisodes cévenol – but meteorologists are concerned that the long, hot summer of 2022 will lead to more extreme storm events than usual this year.
Thanks to the repeated heatwaves, sea temperatures of more than 30C were recorded in July in the Mediterranean off the French coast – some 4-6C higher than is considered normal for the time of year.
“We are used to seeing violent storms [in the early autumn] in the South of France. There are usually about 10 storms per year in the Mediterranean arc. But the warmer the water, the more violent this type of episode is likely to be,” one Centre national de la recherche scientifique expert told Le Figaro.
“The danger [of very violent storms] is very high this year. The energy of these storms is related to evaporation from the sea surface. The warmer the water, the higher the energy.”
This is likely to lead to heavy rains as the atmosphere cools after the summer heatwaves, forecasters say.