Parts of the UK are braced for up to 50cm of snow, as Storm Emma brings worsening conditions.
A highly unusual red weather warning for snow is in force for south-west England and south Wales until the early hours of Friday.
UK roads, railways and airports have been severely hit by snow for a third day, with thousands of schools shut.
Thousands of drivers across the country are stranded in freezing temperatures as police urge people not to travel.
The military has been called in to rescue drivers who have been stuck for several hours on the A31 in Hampshire as police declared it a major incident.
Avon and Somerset police have also declared a major incident over concerns medical staff were unable to get to their place of work.
Police said about 100 vehicles are stuck in snow on the A303 at Ilminster, Somerset, and a rescue operation is under way.
In Dorset, around 100 vehicles are stranded on the A35 near Puddletown and a coach full of elderly passengers have been stuck on roads in Northumbria for eight hours, police said.
The Met Office has 11 live severe weather warnings for snow, ice and wind in place for the UK. The final warning is in place until 23:55 GMT on Monday.
What is happening with the trains?
Across the UK, more than 20 rail operators are running a reduced service.
In London, Paddington Station was closed for nearly three hours due to severe weather conditions, and in Kent 50 stations are closed.
National Rail is reporting mass disruption in the South East, Scotland, north-west England and the South West.
- Virgin Trains’ west coast service to and from Scotland has not been running since mid morning. Trains to Edinburgh are still cancelled and passengers on east coast routes are urged not to travel until Saturday
- Arriva Trains Wales has suspended some services all day on Friday, including trains between Cardiff and Manchester. Some routes are suspended until at least 13:00 while others are running on a reduced timetable
- Heathrow Express services between London Paddington and Heathrow Airport are running less frequently
- East Midlands Trains are unable to run any trains between Nottingham and Skegness
- There are numerous delays and cancellations on the Northern network, with all trains through Huddersfield delayed by up to 50 minutes or cancelled
- ScotRail ran limited services until 19:00 GMT between Edinburgh and Glasgow, Glasgow Central and Kilmarnock and Glasgow Central and Ayr. There will be no trains in the amber warning area during the Friday morning peak
- No CrossCountry services will run in Scotland on Friday