The UK will see a "three-way split" in weather conditions today with a yellow rain warning issued for large areas of northern England, the Met Office has said.
A band of rain stretching from southern Scotland to southwest England will keep temperatures mild in the south and east, but much colder for the rest of Scotland and Northern Ireland.
Drier conditions and sunny spells could see highs of 14C in southern areas, above average for this time of year, while some parts of Scotland will only see highs of 5C to 7C.
A yellow rain warning covering large parts of Lancashire and Cumbria has been issued from 12pm on Monday to 5am on Tuesday, with people being told to be prepared for flooding and disruption to bus and train services.
Up to two inches of rain is expected to fall.
On Wednesday, between 7am and 7pm, there is also a yellow warning in place for wind in the far north of Scotland.
The Met Office said there is a slight chance of damage to buildings and of power cuts.
Met Office meteorologist Craig Snell said: "We've really got a weather front kind of slicing the country and that's where the rain band is - to the south of it we've got the milder air, to the north of it the colder.
"So it's going to be a cold front which is trying to push that milder air away. It probably won't win the day in the south, it will hang on to the milder air for a little bit longer."
Regions caught in the rain will see heavy and persistent showers in places and feel "pretty miserable" until rush hour on Tuesday morning, Mr Snell added.
The latest extreme weather comes after a village in Scotland provisionally set the UK record for temperature in January after hitting 19.6C.
The temperature in Kinlochewe in the northwest Highlands recorded the temperature on Sunday, rising above the previous record of villages Inchmarlo and Aboyne in Aberdeenshire which hit 18.3C in 2003 while Aber, Ceredigion, reached the same level in both 1958 and 1971.
The temperature, if confirmed, would also be the record for a winter's day in Scotland.
In a post on X, the Met Office said: "There has provisionally been a new UK January daily max temperature record set today at Kinlochewe where the temperature reached 19.6C.
"This beats the previous January UK record of 18.3C set at Inchmarlo and Aboyne in 2003 and Aber in 1958 and 1971."