The month of September stands out in Paris from a meteorological point of view. The period was notably marked by a particularly remarkable accumulation of rain, according to data from the official Météo France station located in Montsouris park, in the 14th arrondissement.
113.4 mm of water fell between September 1 and 30, or a little more than 113 liters per square meter. It’s as if it had rained in a single month almost 20% of what it falls on average in a year in the capital. In total, again compared to the average, but monthly this time, it rained 154% more than usual in the capital in September 2024, or two and a half times more than the norm.
A first in the 21st century
This places this month well ahead of the rainiest of the year for the moment. It is ahead of the 95.3 mm of May, this spring month being statistically the wettest of the year in Paris. In percentage terms, March also stood out with a significant surplus. But it was only 90%, not quite twice the seasonal normal.
Such a quantity of water also positions September 2024 as the wettest month of September of the 21st century. To find a wetter month at this time of year you have to go back forty years. In September 1984, the cumulative precipitation had reached 115.4 mm at the Montsouris station, or 2 mm more.
Two weeks of average precipitation in a single day
Last month, five days received more than 10 mm of water. Two stand out: Thursday 5 with 17 mm and especially Wednesday 25 with 22.4 mm alone. On this day, the capital received the equivalent of half of an average month of September and exceeded its average total of rain received in a full year. The standard annual accumulation is 634.3 mm. As of September 30, Paris has already received 659.4. This observation is part of an overall context in the country, with water tables well filled for the season. Furthermore, the month of September was 60% wetter than the average for the whole of France.
In such a humid situation, it is difficult for the sun to penetrate sustainably. The duration of sunshine in Paris in September thus reaches 133 hours and 25 minutes. This corresponds to a significant deficit of 24% compared to the reference normal. Usually, the sun shines for almost 175 hours on the city in September.
Fairly low maximum temperatures
The series of disturbances did not facilitate the rise in the thermometer either. With an average maximum temperature of 20.4°C, the deviation from the norm is -1.1C. This is only the third month of the year to finish below the standards, but above all the one which deviates the most from the reference. The average temperature for the month which ends at almost 17°C is close to the norm. It should be noted that between Sunday 1st with a peak at 29.2°C and Sunday 29th with a maximum of 14.1°C, the thermometer lost half of its value between the start and end of the month .
The situation is similar across the whole of France. Over the whole month, the average temperature is considered close to normal with only -0.4°C difference. The difference reaches 1°C for the maximums, which “leaves a very cool feeling” when it comes time to take stock, explains Météo France.
By the start of next week, maximum temperatures should first stabilize around fifteen degrees in the northern half of the country and around twenty degrees in the southern half, i.e. levels close to average. seasonal. They could then rise by several degrees, which could then give the beginning of October an impression of mildness.
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