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Summer day

When the temperature reaches 25°C or more during the day, it is called a summer day.


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Swiss federal authoritiesSwiss federal authorities

The number of summer days has increased significantly in recent decades. As a result of climate change, summer days are occurring more and more frequently, even in the spring months and into autumn. Moreover, they are being recorded at increasingly higher altitudes. Over the course of the 21st century, the number of summer days will continue to increase. Two consequences of the increasing warming are that vegetation growth onset occurs earlier, and the growing season lasts longer.