And although it didn’t feel like that, it was already too warm again: 11.1 degrees Celsius on average over the past three months – including days and nights – mean fourth place in the data series from the Potsdamer Brauhausberg, which dates back to 1893 and making it the oldest in the region.
“On average, the autumn was two degrees too warm,” says Jörg Riemann, meteorological director of the “Wettermanufaktur” service in Tempelhof. “It was only warmer in 1982, 2006 and 2014.”
September was particularly noticeable due to two completely dry weeks in a row as well as an almost 32 degree hot day in the middle of the month. October, on the other hand, was not golden this year and often fresh during the day, but due to the cloudy and correspondingly mild nights, it was still slightly too warm.
November began at the measuring station in Berlin-Dahlem, which has existed since 1908, with a monthly record of 20.5 degrees on its second day. In Potsdam it was just under a degree colder that day – and the even older series of measurements there even recorded 21.5 degrees in November 1899. “It’s interesting that something like this has happened before,” says meteorologist Jörg Riemann, who is with clear attributions how closely the weather extremes are linked to man-made climate change is always holding back.
40 large buckets of water are missing per square meter
At the end of the third consecutive year of drought, the precipitation balance is even more important. Although September was slightly and October was significantly wetter than the long-term average, autumn is overall too dry. Because in November only 20 instead of the usual 50 liters of rain fell per square meter; since the beginning of the month there was almost nothing more.
Since the beginning of the year, the Potsdam measuring station has had 474 liters – which corresponds to a deficit of 67 liters for the first eleven months. “To make up for that, it would have to rain or snow twice as much in December as usual,” says Riemann.
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With the backlog from the past two years, the rain deficit now adds up to around 400 liters per square meter – 40 large buckets of water. That corresponds to two thirds of a usual annual target. “We don’t have a realistic chance of compensating for that next year,” says Riemann, referring to the statistics: Even in the wettest year since records began, it rained only about 250 liters more per square meter than usual. That was in 2017.
In an internal summer balance of the Berliner Wasserbetriebe (BWB), there is talk of “a record-breaking 198 days” on which the Berliner Wasserwerke pumped above-average quantities. This causes the wells to age faster and “exacerbates a development that is characterized by the increasing demand for water from a growing population, climatic changes and restrictions on the use of the resource due to sulphate, trace substances and nature conservation. To put it simply: More people need more water without the groundwater being regenerated to this extent and in good quality. ”
The winter half of the year is decisive for supplies: In summer, the rain is almost completely absorbed by the vegetation and evaporates.
Now the weather should level off in late autumn and damp cold – without permafrost and heavy rain. “There is no striking warmth in sight like in previous December, but neither is there a really noticeable onset of winter,” says Riemann.