Temperatures dropped to -11.6C in Kinbrace in Sutherland where it was -12.4C at 09:00 on Tuesday.
Milder air has been forecast to arrive from the Atlantic, but bringing with it wet and windy weather.
The Met Office has issued yellow "be aware" warnings for rain falling on frozen surfaces on Thursday and heavy rain on Friday.
Thursday's warning covers large parts of southern, central and western Scotland and Friday's applies to central and southern Scotland.
BBC Scotland weather presenter Kawser Quamer said heavy rain on Friday and snow-melt could increase the risk of flooding in Dumfries and Galloway.
She said: "Last night saw the last widespread cold night for this particular wintry spell.
"There is still a frost in central and eastern areas tonight but in the west milder air seeps in from the Atlantic with some rain and strengthening southerly winds.
"This rain then spreads eastwards during the day on Thursday, with some widespread mist and hill fog - making for quite a dreich day."
She added: "But it's overnight into Friday when more significant wet and windy weather arrives from the Atlantic with much milder conditions, as daytime temperatures widely climb to double figures.
"Friday's rain could enhance flood concerns in Dumfries and Galloway."
Scotland has seen the last widespread cold night of a recent spell of wintry weather, forecasters have said.