The UK had its coldest September night in 23 years after -5C was recorded in Altnaharra in the Highlands.
The same temperature was recorded previously on the night of 19-20 September 1997 at Corgarff and Boultenstone in Aberdeenshire.
The record coldest September night was in 1942 at Dalwhinnie with -6.7C.
Meteorologist and BBC presenter Matt Taylor said an air mass that originated from the Arctic and clear skies had caused temperatures to fall overnight.
He said autumn had arrived "good and proper".
"The reason it was so chilly was due to the air mass across Scotland last night being a rather cold one - the air originated across the Arctic, and with clear skies and the now longer nights, temperatures were able to drop below freezing widely across the northern half of Scotland."
"Some more frosty nights are expected over the coming days, with a small chance we could see the odd spot get even colder than last night."