Further snowfalls held up the post-Christmas return to work, with air, rail and road travel all affected.
Inverness airport in the Scottish Highlands was closed because of the bad weather, while train services to and from Glasgow were hit.
A series of accidents on the roads added to the travel misery, while people in areas where it was not snowing had to contend with rain.
The snow was at its worst today in Wales, with as much as eight to 12 inches (20-30cm) of snow expected later in the day on high ground.
There were also snow showers in the West Country and across the Midlands, north east England and Scotland. Up to four inches (10cm) of snow was expected on high ground later in the day, while long periods of rain were expected in the south.
"You can virtually draw a line from Suffolk to Avon and say that south of that there will be no snow," said Stephen Davenport, a forecaster with MeteoGroup, the Press Association's weather division.
"It could be as mild as 9-10C (48-50F) in the south west of England today but in other areas, such as Scotland, temperatures will struggle to get above freezing. There could be some severe frosts over the next few days."
The Welsh Assembly Government said contingency plans were in place to keep main roads open during the extreme weather. Its stock of salt for motorways was available as a reserve supply to help local councils grit roads, a spokeswoman said.
She said: "We have contingency plans in place in the event of extreme weather to ensure the main roads are kept open and also have encouraged unitary authorities to put in place mutual aid arrangements."
The A66 at Stockton-on-Tees in north east England, the A19 at Sunderland and the A42 in Leicestershire were among the roads where accidents caused delays.