Snow and ice are causing disruption across large parts of the UK for a fifth successive day with fresh snow set to cause further problems.
Hundreds of schools in England, Scotland, Wales and Northern Ireland opted to stay shut.
Flights at UK airports have been cancelled and delayed, and roads and rail networks have also been affected.
Further snow is expected in southern England, and parts of Scotland and Wales into the evening and overnight.
Drivers in parts of Hampshire, Surrey, Sussex, Wiltshire, Dorset, Devon and Somerset are being warned of hazardous driving conditions caused by heavy, fresh snowfall.
A Met Office "be prepared" snow warning for parts of south-west England and south Wales has been issued and is valid until Wednesday morning.
Up to 5cm (2in) of snow is forecast for parts of south-west England with the threat of anything up to 10cm (4in) on high ground and the possibility of blizzard conditions.
The BBC's Susan Powell said some of the worst conditions could be encountered during the evening rush-hour along areas including the M4 corridor and the M5.
The A9 has been reopened near Pitlochry after a crash which left a 70-year-old man injured.
He has been taken to Ninewells Hospital, in Dundee, but his injuries are not believed to be life-threatening.
Grampian Police have urged motorists to exercise extreme caution with drifting snow expected.
Up to 10cm (4in) is possible in Wales with the south-eastern counties again the most likely to see heavy localised falls.
Traffic Wales has warned of hazardous driving conditions on the A470 between the M4 at junction 32, the Coryton interchange at Cardiff, and Merthyr Tydfil.
In Northern Ireland - where the Met Office has issued a warning for icy roads - 5cm-10cm of snow has fallen since Monday, with the bulk of it lying over counties Antrim and Down.
Heathrow Airport cancelled dozens of flights and warned passengers to expect further cancellations and delays.
A Heathrow spokesman said: "Because Heathrow runs at almost 100% capacity there is no slack in the system and flights unfortunately have to be cancelled. Further cancellations are inevitable given the adverse weather conditions at other airports around Europe."
There were also delays at airports including Gatwick, Birmingham, Stansted and Luton.
Eurostar warned passengers to expect delays of up to an hour because of speed restrictions imposed as a result of snow and ice while some services to Paris and Brussels on Tuesday have been cancelled.
Other rail operators including Gatwick Express, Southern and Southeastern also reported cancellations and revised timetables.
National Rail said all UK train companies were expected to run a full service on Wednesday.
There have been school closures:
Thousands of schools were closed on Monday. While many children enjoyed sledging, injuries were reported by ambulance services.
Sixteen-year-old Liam Stafford remained critically ill in hospital after hitting a tree while sledging in Normanby, Middlesbrough.
East of England Ambulance Service also issued a warning after it was called out to attend at least a dozen sledging-related injuries, including broken bones or head injuries requiring hospital treatment.
The cold conditions have claimed some lives. A Somerset postman died while carrying out his rounds in freezing conditions on Exmoor, Royal Mail has confirmed.
It is believed John Bircham had a heart attack after trying to free his van from a snow drift on Saturday.
And on the A12 in Essex on Monday night a driver died when his car left the road and collided with a tree.