A so-called tropical night – a night when temperatures don't fall below 20C – was recorded at 11 official weather stations run by national weather agency SMHI between Saturday and Sunday.
They were Karlskrona, Malmö, Utklippan, Falsterbo, Skillinge, Öland north and south, Hanö, Harby and Skurup in southern Sweden – and according to SMHI it's a rare phenomenon this late in the season.
Last time this happened in a September month was on September 5th 2002 at northern Öland.
Central and northern Sweden also had unseasonably high temperatures over the weekend, and the eastern Götaland region on Sunday looked like it was in with a shot at possibly beating the September record of 29.1C (set in Stehag in the southern Skåne region in 1975).
It followed a warm week in general, with 31.6C registered in the university town of Lund in southern Sweden on Tuesday. That's the highest temperature this August, according to preliminary figures.
When cooler air started moving in on Sunday afternoon, the clash with the mini heatwave caused thunderstorms, prompting SMHI to issue a class-two (on a scale from one to three) warning.
Sunday – söndag (note that days of the week are lower case in Sweden)
Saturday – lördag
heatwave – (en) värmebölja
tropical night – (en) tropisk natt
thunder – åska
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