A blanket of snow likely to cover the UK on Friday
Hundreds of schools have been closed and transport disrupted as a band of heavy snow affects most of the UK.
Cardiff, Bristol and Southampton airports are closed and part of the M4 was shut in Wales. Train companies have put revised timetables in place.
A rare red Met Office warning for snow is in place for parts of Wales, meaning severe disruption is likely.
There is an amber warning for Northern Ireland and most of England, with snow also due in parts of Scotland.
There have been widespread school closures in England with over 400 in Hampshire and the Isle of Wight, and 300 in Norfolk, while 300 schools and colleges have been closed in Gloucestershire. In Wales, 1,100 schools have been closed.
Blizzards and strong winds are set to make driving conditions difficult on the roads, and motorists are being warned that heavy snow will arrive in many areas before the morning rush-hour.
Driving has been described as "tricky" on the M5 in Somerset, particularly around Bridgwater and Burnham, with reports of one lane being impassable in some places.
The Met Office's red warning for snow, which is unusual and means all non-essential travel should be avoided, applies to the south-eastern side of the Brecon Beacons and Black Mountains until 21:00 GMT on Friday.
Red warning areas could see up to 30cm of snow and blizzards.
Amber severe weather warnings, which mean be prepared for disruption and only travel if necessary, are also in place until at least 21:00 GMT across large parts of central, western and southern England and Wales, as well as Northern Ireland.
BBC Weather said Northern Ireland would experience rain early on Friday, which would turn to snow during the course of the day, with between 10cm and 15cm expected in most areas and about 20cm over hills.