The Met Office says the high pressure system that had been responsible for the dry and mild weather of last week is shifting out to the south, introducing colder Arctic air from the north.
This brings with it the risk of unsettled conditions for many from late Tuesday and into Wednesday.
On Wednesday there’s an ongoing chance of a wintry mix of precipitation for most, with rain and sleet more likely on the lower ground, although flakes of snow remain possible in places, albeit unlikely to settle for any length of time.
Higher ground in the northeast, and even further south, could see a few cm of slushy wet snow in places, but this will likely melt quickly on Thursday morning.
Coupled with the sleet and snow is the drop in temperatures that many places have already been experiencing.Sub-zero temperatures are also forecast overnight for much of the UK throughout the week.
The unsettled theme will continue through to the weekend, with the cold front clearing the far southeast on Thursday morning, followed by wintry showers for many places on Thursday and Friday, ahead of a continued unsettled weekend.
Temperatures are likely to gradually recover to near-average over the weekend and into next week.
Met Office Chief Meteorologist Steve Willington said: “Cold and unsettled weather is taking charge over much of the UK this week, as cold air is drawn in from the north and brings with it the risk of rain, sleet and snow.
“Although there’s still some uncertainty on the exact positioning of snow showers, the trend is for a mix of sleet and snow to fall as a cold front moves from the north to the south from late on Tuesday through to Thursday morning. Some clear spells are still around later in the week, with the best of any sunshine likely to be in the south and west of the UK, albeit feeling cold compared to last week.”