The update of this August 10 concerns the meteorological autumn with the months of September, October and November. In the context of historic drought that France is experiencing this summer, the forecast of precipitation is of crucial importance because effective rains are needed in autumn. Unfortunately, the numerical model developed by Météo Consult predicts an autumn still largely lacking in rain.
The meteorological configuration for this summer 2022 remains exceptional due to the persistence of high pressures in July and August. The recurrence of heat waves and the rarity of storms resulted in a drought comparable to those of 1976 and 1983, for example. In this context, the rains would be necessary in autumn and winter in order to infiltrate the soil and feed the groundwater. But so far, the recurrence of high pressure seems to be predominant for the next three months.
September: a rather dry and hot month
The forecasts drawn up on July 10 remain valid, which is a sign of good reliability. The month of September could be beautiful and warm, appreciated by late-season vacationers. High pressures would again remain predominant over the British Isles and the North Sea, while stormy lows would form over Spain. The storms would remain relatively short-lived, with a rainfall deficit across France. Mediterranean storms are expected, rather on the Languedoc-Roussillon side, with excess precipitation in this sector. Given the high temperature of the Mediterranean, these episodes could be particularly strong, although water temperatures are not the only factor conducive to the violence of these bad weather. Temperatures would be around +1°C higher than normal and precipitation would be lower than normal for the season by around 30 to 40% with disparities in the south-east.
October: towards a dry and cool autumn month
Here too, the forecasts drawn up already in July have been confirmed, with the persistence of high pressures over the near Atlantic, which is synonymous with the maintenance of a dry trend. On the edge of the Atlantic anticyclone, France would be subject to northerly currents, dry but cool, with temperatures slightly below average. In this context, we can expect the first early frosts in our country. To the southeast, the northerly flow would be favorable to the prevailing mistral, limiting the risk of Mediterranean episodes. That doesn’t mean there wouldn’t be any in October, but possibly in isolation. In this regard, the rainfall deficit forecast for October is close to 50%, especially in the west, closest to the anticyclone. Meanwhile, low pressure systems would bring cold and rainy weather to central Europe.
November: another month with a rain deficit
High pressure anomalies would still be present over France in November, while depressions would rather circulate off the Mediterranean. In this context, the weather would generally remain calm and dry, which does not exclude the passage of disturbances all the same, but with total rains 30% lower than the statistical averages. The dominant flow directed to the southwest or to the south could bring new Mediterranean episodes, especially on the Spanish coast, but could concern the south of France. Temperatures would be about +1°C higher than average.
In conclusion, our seasonal forecasts confirm a hot summer in France, with an excess close to +1.5°C to +2°C above the three-month averages. On this subject, and depending on the difference that this month of July will ultimately present, our summer 2022 will probably be in the top 3 of the hottest observed in France since 1900, with 2003 and 2018.
But the real signal that emerges from these three-month forecasts is the persistence of a dry underlying trend until autumn. The Cévennes and Mediterranean episodes could start in September, but our modeling seems to envisage a more active rainy season in November and December, while October would be rather dry. This persistent rainfall deficit is a real cause for concern because our country has been suffering from drought since the winter. If the water tables do not fill up during the coming cold season, the year 2023 would then be particularly critical in terms of water resource management.