November brings twice as much rain as average
Published: Wednesday, Nov 29th 2023, 16:20
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The feeling was not mistaken: in most areas of Switzerland, precipitation fell almost daily from November 1 to 25. The rainy month ended one of the warmest autumns since records began.
In western Switzerland and the central and eastern midlands, twice as much rain had already fallen by the middle of the month as usual during the whole month, as MeteoSwiss reported on Wednesday.
By the end of the month, rainfall on the northern side of the Alps had reached well over 200 percent of the 1991-2020 monthly norm in some places, and locally even more than 300 percent. Certain areas in the Schaffhausen region even recorded the wettest November since measurements began.
Three days of constant rain
The rainfall reached a peak in the middle of the month: from November 12 to 15, there was the kind of sporadic rainfall that can only be expected every 10 to 25 years. On the northern side of the Alps and in Valais, there was between 60 and 90 milliliters of precipitation in these three days, in the east even between 100 and 150 milliliters and on the Säntis 219 milliliters.
In general, however, such amounts of precipitation are not unusual on the northern side of the Alps and can be expected every one to three years. In the south and in a large part of the canton of Graubünden, it even rained less than average in November.
Warmest regional fall since records began
November temperatures were also within the normal range. However, the entire fall of 2023 was the warmest since measurements began in 1864 at several measurement locations north of the Alps. In Geneva, for example, temperatures from September to November were 2.4 degrees above the 1991-2020 norm.
The reason for this was the record number of hours of sunshine measured: 477 in Geneva (previous record: 470) and 476 in Neuchâtel (previous record: 470). Lucerne also experienced the sunniest fall since measurements began with 436 hours of sunshine (previously: under 400).
The warm autumn and the lack of cool nights also meant that the deciduous trees stayed green for an unusually long time this year. According to MeteoSwiss, leaf coloration took place seven to 12 days later than the average for 1991-2020. In the case of beech, it was one of the three latest since observations began in the 1950s.
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