A number of UK airports have closed and rail services delayed as the big freeze continues to bring the UK to a standstill.
Leeds/Bradford, Liverpool and Manchester airports closed earlier due to heavy snowfalls and ice on the runways, and easyJet has been among the many airlines forced to cancel dozens of flights from both UK and European airports.
Snow fell overnight in Scotland - where temperatures were -15C in places - in north Wales and northern England.
Snowfalls of up to 30cm (12in) have been forecast for southern England.
Commuters faced major delays, with accidents and jams on several motorways.
Train operators including Virgin Trains and East Coast Arriva Trains Wales, Cross Country, First TransPennine Express, Northern and Scotrail were all reporting disruption.
Liverpool and Manchester Airports have now reopened, although there have been many delays and cancellations.
Passengers at London Heathrow, Gatwick, Edinburgh, Glasgow and Aberdeen airports all faced disruptions.
The temperature is expected to hover around freezing across much of the UK.
Hundreds of schools in northern England and the south-west also closed on Tuesday after heavy snowfall. More than 250 schools have closed in West Yorkshire, and 102 in Cornwall.
Meanwhile, motorists in many areas were being warned to make only essential journeys and to prepare themselves with warm clothes and blankets in case of breakdown.
Driving conditions in Northern Ireland and Wales worsened with rain, sleet and snow falling on already icy roads and pavements.
Most councils said they had enough grit but a number in Wales said they would only treat main routes to preserve stock.