In many temperate zones, this has long been considered an anomaly. The so-called “tropical” nights, during which the thermometer never drops below 20°C, are becoming more frequent and more frequent throughout France. This is a direct consequence of the warming of the atmosphere, which weighs on the most fragile organisms and pushes some to equip themselves with air conditioning to preserve their sleep.
During the summer just past, which was rather mild in part of the country, Nice experienced sixty consecutive nights of this type. During the summer of 11-12 August, the thermometer remained at 28.1°C in Menton (Alpes-Maritimes). Before the storms broke out during this stifling period, Marseille recorded twenty-eight consecutive nights with temperatures above 20°C, Cannes twenty-six, and Perpignan twenty.
“This doesn’t surprise us, but it still scares us a little when we look at the data.summarizes Matthieu Sorel, climatologist at Météo-France. We are witnessing an increase in these episodes in the south and a very clear increase in the phenomenon towards the north of France. No region is safe anymore. »
The Mediterranean, “thermal regulator”
On Mediterranean cities, data from the last decade collected by Météo-France and consulted by The world They are impressive. the 1Ahem In August 2017, the thermometer remained stuck at 30.5°C in the middle of the night in Marignana, Corsica. An absolute record.
In 2022, the city of Nice experienced one hundred and four tropical nights, including sixty-nine in a row, another record. In this city, the series has been accumulating for ten years: ninety-three in 2018, eighty-two in 2019, eighty-nine in 2023, seventy in 2024. A clear marker of climate change. Indeed, between 1943 and 1952, the capital of the Alpes-Maritimes recorded, on average, only twenty-two “tropical” nights per year. Since 2015, no year has passed with less than seventy nights above 20°C.
“Like everything related to temperatures, it is a direct consequence of global warming, although there may be local variations depending on cloud conditions or the morphology of the environment.”analyses Robert Vautard, co-chair of Group 1 of the Intergovernmental Panel on Climate Change (IPCC).
According to a report by INSEE Provence-Alpes-Côte d’Azur, published on May 21, 79% of the population of this region will be exposed to “tropical” nights during the period 2021-2050, while this rate is not only 35% during the period 1976-2005, “mainly in part of the coastal strip”. “The Mediterranean Sea acts as a thermal regulator, it can soften temperatures during the day but also keep them at a very high level at night.deciphers Mr. Sorel. It increases the humidity level, which adds a very unpleasant humidity that, combined with the heat, can have significant health consequences. »
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