France is beginning an "early but not unprecedented heatwave," according to Météo-France.

With 25°C exceeded in most regions, and 30°C forecast in Paris for May 1, France is experiencing an "early but not unprecedented heatwave," Météo-France explained on Wednesday, before a significant cooling period from Sunday.

"This episode of unseasonably warm weather will not, in principle, be exceptional," predicts the national meteorological observatory, recalling that "it has already been a little warmer a little earlier in the season."

In 2024, an early heatwave hit France from April 5 to 8, three weeks earlier. Also in 2018, "the mercury exceeded 25°C across the country" as early as April 21, "and there are plenty of examples," notes Météo-France. The event, expected to last through Saturday, is "comparable" to that of 2005, when temperatures on May 1 approached 29°C in Paris, 30°C in Strasbourg, and exceeded 31°C in Dax.

It is on the coasts of the Channel and Brittany "that this episode will be the most remarkable, with locally a difference (...) of 10°C" above the average for the years 1990-2020, already itself warmer than in the 19th century.

Heat waves have become more frequent and earlier in France, where the average climate is at least 1.7°C warmer than in the pre-industrial period, before the massive combustion of coal, oil and gas.

Over the past 25 years, the period from late April to early May has seen four similar heat waves lasting four days across the country, Météo-France told AFP. "Before 2000, we were still able to record higher temperatures occasionally at this time of year, but not over a series of four days," it added.

This heatwave is not classified as a " heatwave ," a term reserved for summer events where the "national thermal indicator" - that is, the average temperature recorded at 30 representative points in mainland France - "must exceed 25.3°C for three consecutive days," which has never happened in April or May. The earliest national "heatwave" was observed from June 15 to 19, 2022.