Snow is already causing some travel disruption in the UK this evening, particularly in the south west of England.
Around 100 cars are stuck on the A30 at Temple near Cornwall and Newquay airport was temporarily closed earlier.
Chief Inspector Adrian Leisk, head of roads policing across Devon, Cornwall and Dorset, said around 100 vehicles were stuck on the A30 in Cornwall.
He tweeted: "Significant snowfall in #Cornwall, particularly on the A30 at Temple where around 100 vehicles are currently stuck.
"The snow is heading eastwards and will cause significant disruption tonight. Please be prepared and avoid all but absolutely essential travel."
Highways England said that around 100 cars became stuck on the A30 near Temple in Cornwall because of a whiteout.
A plough and a gritter have been sent to assist the stranded motorists, a spokeswoman for the organisation confirmed.
Snow depths of 5cm have been recorded in Bodmin, Cornwall, and Sennybridge, Powys, the UK's Met Office said.
The snow is moving eastwards across southern England and Wales and has also fallen in Wiltshire, Hampshire, Sussex and Kent, according to the forecaster.
An "intensive effort" is under way to help stranded motorists on the A30 in Cornwall, said Chief Inspector Leisk.
He tweeted: "For those stuck on the A30 in Cornwall, an intensive effort is under way to clear the carriageways of vehicles to allow the gritters through.
For those stuck on the A30 in #Cornwall, an intensive effort is underway to clear the carriageways of vehicles to allow the gritters through. Please stay with your vehicles and we will get to you. @HighwaysSWEST and @CornwallCouncil working closely with us to get things moving— Ch Insp Adrian Leisk (@Adrianleisk) January 31, 2019
"Please stay with your vehicles and we will get to you."