Ever more present. Since this Tuesday, July 18, 2023, a heat wave has been hovering over a large majority of the departments of French territory. Indeed, this rise in temperatures is caused by the heat dome that crosses southern Europe. This phenomenon should continue on Wednesday July 19, 2023 until late at night.

“For a few days, this torrid air from North Africa also concerns the south-east of France as well as Corsica”, announces the editorial staff of La Chaîne Météo. For the past three days, temperatures have been approaching heat wave thresholds. “Corsica, placed on orange alert, is undergoing the most lasting episode of heat wave, until the end of the week”, specifies the meteorologists.

Usually, the heat softens to give way to more breathable temperatures for the night. However, this night of July 19 will mark an exception on the scale of certain French territories. In its Wednesday bulletin, Météo France confirms this and also warns of the lack of cooling overnight. “We measure at 5 a.m.: 26°C in Montpellier and Béziers, 25°C in Marseille and Nice, 24°C in Arles. It is also very hot in Corsica, with temperatures between 24 and 29°C. ” This phenomenon bears a name still unknown to the French, but which could well become widespread: “tropical nights”. These are aptly named since during these periods the mercury does not drop below 20°C. Moreover, as the National Institute of Sleep and Vigilance reminds us, these hot nights are much less restorative for the body.

Worrying. This phenomenon occurs throughout France, but particularly affects the south of France. The cities located on the shores of the Mediterranean are the most impacted. “Unlike the Bouches-du-Rhône, the mistral does not blow on these coastal towns of the Var and the Alpes-Maritimes. The wind cools the sea because it stirs it up”, explains Météo France. Even less reassuring: this phenomenon will last throughout the summer and could only end next September. For comparison, in 2022, the last tropical nights were on September 16.

Discover without further delay in our slideshow, the 13 departments affected by heat wave vigilance until late at night on Wednesday July 18, 2023.