Heavy snow caused travel misery for many Britons today - suspending flights, disrupting rail travel and sparking a series of road accidents.
Lengthy queues formed on Britain's roads with several accidents closing motorway lanes and major A roads.
There were three accidents on just one stretch of the M5 in Gloucestershire, while the M6 was also hit by an accident at junction 10 near Wolverhampton.
However, many commentators said that problems were not as bad as some had predicted, with many workers leaving their cars at home.
Drivers were tonight warned to be extra careful as freezing temperatures would bring icy conditions overnight and into the morning.
Bitterly cold temperatures look set to stay for the weekend.
Several airports were forced to ground flights or close following thick snow flurries and near gale-force winds of 30mph.
A spokesman for Heathrow - which shut both runways for periods during the day to clear snow - said 369 flights were cancelled.
Bristol and Birmingham airports closed for a time while Southampton stayed shut for most of the day.
Flights in and out of Gatwick escaped major disruption but the airport advised passengers flying out this weekend to contact their airlines to check flight status.
South Wales had to bear the brunt of the wintry weather first thing, with a rare "red warning" in place from the Met Office there and up to 30cm - a foot - of snow expected.
The deepest snowfall was measured at 26cm in Sennybridge, Wales, although snow has been thawing in other areas and some train services have been returning to normal.
At first the Home Counties were spared the early-morning flurries, with millions leaving home for work before snow showers spread eastwards.
More than 1,000 schools in Wales were among those shut for the day, with many sixth-form and college students having their A-level exams postponed and others having to trudge through the snow for exams that were going ahead.
Most of the UK saw temperatures hovering around zero - but these will plunge below freezing in many areas tonight.
Amber alerts are in place for the Midlands, London and the South, the east of England, the South West, the North West, parts of eastern Scotland, Wales and Northern Ireland.
In Wales, a power cut left 10,000 people without electricity. There were reports of panic-buying in South Wales, the West Country and the Home Counties as shops ran low on stock.
Merthyr Tydfil has been among the worst hit areas and the A4232 leading into Cardiff was packed with commuters who left home despite the conditions. The closure of a section of the M4 at Bridgend caused morning rush hour headaches for many.
There were severe hold-ups for rail passengers, with many companies cancelling services to help them cope with problems caused by the weather.
Eurostar axed four services between London and Brussels. Train firms are advising passengers to check with operators before travelling.
While commuters have been facing misery, the winter wonderland scenes have brought joy to thousands of youngsters who got the day off.
Herefordshire, Worcestershire, Warwickshire and Staffordshire were particularly badly hit, with almost 700 schools deciding to close across the four counties by the early afternoon.
In the Scottish Cairngorms a mountain rescue operation was launched for a missing walker who became separated from her party in bad weather. She was later found safe and well.
Few parts of the UK will escape the wintry weather as it continues into the weekend.
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There is up to 10cm of snow likely in northern and eastern England as well as Ireland and southern and eastern Scotland on Saturday. Snow elsewhere will be lighter but it will be bitterly cold.
Sunday could also bring persistent but light snow to southeast England and some flurries for Scotland.
Darron Burness, from the AA, said commuting in the wintry conditions was "likely to test man and machine".
Those who decide to travel have been urged to travel prepared with a fully charged mobile phone, warm waterproof clothes, boots and a blanket, some food and drink, and have a torch, ice scraper, de-icer and a shovel.