Overview

Is climate change causing more heat waves and hot days in Germany?

In the 1950s, Germany experienced, on an annual average, around three “hot days,” which is what meteorologists call those days when the temperature rises to 30 degrees Celsius or higher. Between 1991 and 2019, the number of “hot days” had already increased to 8.8 days per year on average. In contrast, the average number of “below-freezing days,” i.e., days when the temperature remains below 0 degrees Celsius all day, decreased from 28 to 19 days per year during the same period.¹ In winter 2019/2020, Hamburg, for example, did not experience a single below-freezing day – a first since record-keeping began.²

The frequency and intensity of heat waves in Germany has also changed, with many regions having recorded a massive increase in these events since the 1990s. For example, 14-day heat waves with a mean maximum air temperature of at least 30 degrees Celsius did not occur at all in Hamburg before 1994. Since then, the city has already had five such hot spells. If greenhouse gas emissions go unchecked, researchers expect to see a further increase of five to ten hot days in northern Germany and of ten to 15 hot days in southern Germany for the period from 2021 to 2050.³

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¹ www.dwd.de/zeitreihen
² https://www.hamburg.de/pressearchiv-fhh/13757034/2020-03-25-bue-winter/
³ Brasseur/Jacobs/Schuck-Zöller (Hrsg.): Klimawandel in Deutschland. Springer-Wissenschaft 2017, S. 138 – https://www.springer.com/de/book/9783662503966; Auswertung des Institut für Wetter- und Klimakommunikation 2012; https://isabel.dwd.de/DE/leistungen/nationalerklimareport/download_repo…