the 40°C threshold exceeded more and more frequently in France

The mercury is rising in the South. While Météo-France placed 56 departments on orange heatwave alert on Tuesday, July 30, with the thermometer already crossing the 40 degree mark three times since Sunday, in Var, Hérault and Ardèche. A classic for the season? Not quite. “For many people, summer is hot, and we have always known these temperatures, but it is false”immediately asks Matthieu Sorel, climatologist at Météo-France. “In the 1970s, we reached peaks of 30 to 35°C. The threshold of 40°C was practically never reached. Today, it is no longer rare to exceed it”he sums up, questioned by franceinfo.

“Of Decades after decades, the 40°C threshold is crossed more frequently in Franceunderlines the weather forecasting institute. Since 2000, this has happened on average thirteen times a year, compared to once a year between 1950 and 1999.” According to data transmitted by Météo-France and from 91 stations, this threshold has been exceeded every year since 2015, while between 1951 and 1999, the 40°C threshold was only exceeded for six years. In 2003 and 2019, it was exceeded 58 times, and around thirty times in 2022 and 2023.

“It’s a threshold that we didn’t look at too much before because it was episodic. We are becoming more and more interested in it because it is a good marker of global warming.”points out Matthieu Sorel. With the rise in temperatures on a global scale, mainly linked to the combustion of fossil fuels (coal, oil and gas), heat waves are gaining in intensity, frequency and duration. “Now we reach 40°C earlier in the year”the climatologist points out. In 2022, the thermometer had displayed 40°C in Hérault on June 16, a record for precocity in mainland France.

“It is often in Corsica that we record these temperatures from mid-June, because the island experiences episodes of sirocco”a very hot wind from the Sahara that rarely reaches the rest of the territory, says Matthieu Sorel. A trend that should continue. “In the current dynamics of climate change, we expect to cross these thresholds more frequently, from the beginning of June to the end of September.”he believes.

This symbolic threshold is not only crossed more frequently and earlier, but also over a larger part of the territory. “Before, it was exceeded mainly in the south-east quarter and in the south-west. Little by little, it began to be crossed in regions further and further north”assures Matthieu Sorel. For example, Dunkirk, in the North, recorded 41.3°C in 2019.

“From now on, no geographical region is safe from exceeding the 40°C threshold.”

Matthieu Sorel, climatologist at Météo-France

to franceinfo

The phenomenon also reached higher localities in 2023, with 40.6°C in Verdun in Ariège (at an altitude of 550 metres) and 40.4°C in Serralongue, in the Pyrénées-Orientales (at an altitude of 700 metres). The only two departments that have never recorded a temperature above 40°C are Bas-Rhin and Territoires du Belfort.

Since the 19th century, the average temperature of the Earth has warmed by 1.1°C. Scientists have established with certainty that this increase is due to human activities, which consume fossil fuels (coal, oil and gas). This warming unprecedented in its speed, threatens the future of our societies and biodiversity. But solutions – renewable energies, moderation, reduction of meat consumption – exist. Discover our answers to your questions about global warming.