Fresh heavy snowfalls and icy roads affecting the UK
Severe weather warnings are in place for parts of the UK with more heavy snow falling in some areas.
In north-east England, 35cm (14in) fell overnight and police are warning people only to go out in emergencies.
Parts of Scotland may get another 15cm (6in) on Saturday, with more likely in Northern Ireland. Ice is making driving dangerous in many regions.
Norwich, Inverness, Newcastle, Luton and Durham-Tees Valley airports are all experiencing disruption to flights.
Some weekend sporting events have also been cancelled.
The UK has seen the earliest widespread snowfall for 17 years and forecasters say it could last for two weeks.
One of the coldest places overnight on Friday was Trawscoed, in west Wales, where -10.2C (14F) was recorded. Dalwhinnie, in the Highlands, recorded -8.2C (17F), and Chesham, in Buckinghamshire, -7C (19F).
There are Met Office severe weather warnings for heavy snow in Orkney and Shetland, Highlands and Eilean Siar, Grampian and Lothian and Borders.
There are also warnings for north-east England, where another 10cm (4in) could fall on Saturday afternoon. Northern Ireland could get up to 5cm (2in).
Travel is disrupted in some areas, especially north-east England, and coastal areas, in particular, have fared badly.
The A1 - the main east-coast link between England and Scotland - is down to one lane, and rail passengers using the East Coast line are also being warned of delays because of poor weather conditions.
Driving is difficult across much of Wales, Scotland and north-east England.
Johnny Graham, a snowplough driver in Longhorsely, Northumberland, said: "All the roads are treacherous. There's snow [and] cars stuck everywhere.
"[We're] just trying to get them clear as quickly as we can. It's a lot worse than past years I've seen - besides last year - it's bad, very bad."
Inverness airport is currently closed, with flights delayed or diverted. Norwich airport was closed until 1200 GMT, and delays are ongoing, while in Jersey, a lightning strike disrupted radar equipment, leading to flight problems.
BBC weather forecast Darren Bett said: "It's the sea temperatures that are higher than the land temperatures that are helping to trigger this instability and trigger those showers - which is why we are seeing a lot of them near the coast.
"It is very treacherous on Saturday morning."
There are Met Office warnings in place for more heavy snow in north-east England on Sunday. South-coast counties could also experience flurries.
Met Office forecaster Charles Powell added: "The snows will move west over the Pennines into Cumbria and by Monday morning could have reached Manchester."
Motoring body the AA said it had been a very busy morning, with the most call-outs around Newcastle, mid and north Wales, Norwich, Leeds and Bradford.
"By 10am we were up to 2,800 breakdowns for the day, coming in at 900 every hour," a spokesman said.
"On that basis we will probably exceed 12,000 by the end of the day, up 40% on a normal Saturday in November.
"There are lots of flat batteries and lots of people failing to get out of the driveway."
Saturday's horse racing meeting at Newcastle has been cancelled, with Gosforth Park under 18cm of snow. The meeting at Towcester, Northamptonshire, has also been called off, as have Sunday's events at Leicester and Carlisle.
Several football matches in Scotland, including Sunday's Alba Cup final, are off.
No Football League games have been cancelled, but Hartlepool's FA Cup tie with Yeovil has been postponed and the match between Darlington and York is in doubt.
Newcastle United have drafted in extra staff to try ensure Sunday's clash with Chelsea goes ahead.
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Disruption due to winter weather began on Thursday and worsened on Friday.
On the M4 in south Wales there were reports of a 26-mile tailback in the Friday evening rush hour westbound from the Severn Bridge toll booths to Miskin, while more than 160 schools had earlier been closed or partially closed in Scotland.
Schools in Northumberland, Tyne and Wear, East and North Yorkshire, and Wales were also affected, and flights were disrupted at Newcastle airport.
Animal charity the RSPCA is urging dog owners to keep pets safe by avoiding iced-over lakes or ponds.
The unusual weather is being caused by high pressure over Greenland and low pressure in the Baltics, forcing cold winds from the north-east across Europe.