Number of "warm nights" in NL tripled since 1950

The number of "warm nights" in the Netherlands, in which minimums did not drop below 18 degrees Celsius, roughly tripled since the second half of the last century, KNMI reported on Friday. The number of "tropical nights", with minimums of 20 degrees or higher, also increased.

The meteorological institute compared the number of warm nights at five of its weather stations - in De Kooy, De Bilt, Eelde, Vlissingen, and Maastricht - in the period of 1951-2000 with those in 2001-2019. This showed that minimums of 18 or higher are nearly three times more common in this century than in the period of 1951 to 2000. 

Vlissingen had the most warm night this century, counting an average of 13 a year. In the period 1951 to 2000, thermometers did not drop below 18 degrees in Vlissingen an average of four times a year. Eelde counted the fewest warm nights at an average of 3 per year this century, and one per year in the previous one.

"In general, the number of warm nights increases as the location is further to the south and closer to the sea," the KNMI said. "You can see the damping effect of the sea on temperature fluctuations here."