The big freeze gripping the country will get worse this week, with snow spreading inland and some temperatures plunging as low as minus 20C, forecasters have warned.
Deep snow and freezing conditions in the North East and Scotland have been causing widespread travel disruption, with icy temperatures everywhere else creating similar problems for commuters.
There is no sign of a let-up in the wintry weather, with bitter winds increasing and more parts of the UK facing snow in the coming days.
The RAC warned of a "difficult" Monday commute and told drivers to consider other options.
The cold spell saw record low temperatures in some parts of the country over the weekend, with both Wales and Northern Ireland recording the coldest November night since records began.
Coldest overnight in the UK was Altnaharra in northern Scotland, which recorded a low of minus 16.1C (3F).
Llysdinam, which saw Wales's chilliest ever November reading on Sunday at minus 18C (minus 0.4F), was a bit warmer today at minus 12.9C (8.8F).
The temperature in Northolt, west London, bottomed out at minus 2.2C (28F), but it was colder in the South West, with North Dartmoor recording minus 7.9C (17.8F).
So far, Scotland and the North East have been worst hit by snow, with more than 40cm in parts, and police have advised people to stay indoors for all but essential travel.
Several airports were disrupted on Sunday, with Edinburgh closed due to heavy snow, Aberdeen suffering delays and Newcastle International, Luton and Jersey also seeing disruption.
Forecasters warned the rest of the country is likely to be blanketed this week as the weather front moves west. The severe conditions could also last well into next week, with rain, sleet and snow.
The Arctic conditions have been caused by a combination of light winds, snow cover and clear skies - and could see readings down to minus 20C in Scotland later this week. The UK's lowest ever recorded temperature in November was minus 23.3C recorded in Braemar, in the Scottish Highlands, on November 14, 1919.
The AA said it dealt with double the normal number of breakdowns on Sunday, while the RAC said calls were up a third. Alan Wilcock, RAC patrol ambassador of the year, said: "With more bad weather forecast, the Monday morning commute is already looking very, very busy. Workers who travel by car may want to consider other options, such as working from home or another form of transport."
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