September 2024 was the wettest September in a quarter of a century.
In terms of temperatures, however, it was consistent with seasonal norms despite a feeling of freshness.
A late summer and early fall marked by rain. “With a rainfall excess of almost 60% compared to 1991-2020 normals (119 mm), September 2024 becomes the wettest month of September in 25 years”announced Météo-France this Monday. The past month ranks behind September 1999, with 130 mm recorded on average, according to the institute’s monthly climate bulletin.
More than double the normal in places
“There is excess rainfall over almost the entire country” et “even reached more than double the normal in New Aquitaine, in the Massif Central, the Paris Basin, the Channel coasts, as well as in the Northern Alps and in the north of Corsica”note Météo-France.
At the beginning of September, in the Pyrénées-Atlantiques, the Aspe valley was notably the scene of destructive floods, while the Alpes-Maritimes suffered a Mediterranean episode pouring a month and a half of rain in 24 hours on towns like Fréjus or Mandelieu -la-Napoule.
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For a large part of the territory, this excess rain has been a constant since the start of the year, with average annual totals already exceeded in nine months in Nice, Saint-Nazaire, Strasbourg and Le Mans and in the capital. In Paris, the cumulative rainfall reached “660 mm since January 2024, compared to 634 mm average annual total”according to Météo-France.
“Only the south of Brittany, Languedoc and Roussillon have a rainfall deficit”particularly marked in the Pyrénées-Orientales (-30%), with a very serious precipitation deficit for more than two years.
In terms of temperatures, despite a “feeling of freshness”the national average in September was “close to normal”being only 0.4°C lower than the period 1991-2020. A tiny difference compared to +3.6°C in 2023, to date the hottest month of September ever measured in the country.
