Cold winds, frost and even some snow are to hit Britain this week, signalling the end of the October heatwave.
The mercury peaked at an unseasonably high 18.3C (64.94F) in Gravesend, Kent, yesterday but temperatures are set to drop in the coming days.
Andy Ratcliffe, a forecaster at MeteoGroup, the weather division of the Press Association, said: "A cold front will start across Scotland and Northern Ireland tomorrow, giving some heavy outbursts of rain, which will turn to snow over the mountains in Scotland.
"The rain will spread further south into northern England and Wales by the end of tomorrow."
Winds of up to 65 miles per hour are expected across north-western England, Scotland and Northern Ireland, and the odd rumble of thunder is possible.
"We will definitely feel a chill in the air," Mr Ratcliffe said.
"The winds originate in the Arctic, but they get modified a lot as they arrive here."
Although the south of the country will enjoy highs of up to 17C (62.6F) today and tomorrow, it will feel much cooler across the UK on Tuesday, with highs of 14C (57.2C) in the south and 10C (50F) in Scotland.
"There will be heavy showers, mainly across northern and western areas, with the chance of the odd rumble of thunder," Mr Ratcliffe said.
On Wednesday night, temperatures will plunge to around 1C (33.8F), and could be as low as -1C (30.2F) in northern parts of the country.
Mr Ratcliffe said: "It's going to be pretty cold everywhere across the UK on Wednesday night, with widespread ground frost expected in the whole of the UK and perhaps air frost in places too."
However, by the end of the week conditions should be milder as a result of weather systems moving in from the Atlantic.
The cooler weather comes after record-breaking 29C (84.2F) days at the beginning of October.