The Met Office has issued a red warning, the highest level available, with heavy snow expected to cause major disruption across the country.
Hundreds of schools and roads have closed after heavy snowfall overnight across large parts of the United Kingdom.
Parts of central Scotland, ranging from Edinburgh to Glasgow, are covered by the red warning from 3pm GMT, meaning that there is a high risk to life.
The warning urges people to take immediate action to keep themselves and others safe from the impact of the weather which is expected to bring widespread damage.
Across the rest of Scotland, northern and eastern England, amber warnings are in place.
Police have urged drivers to avoid driving to some locations if at all possible, with delays on roads and motorways.
Overnight lows dropped to -12C in some places and created delays on public transport networks.
Trains and flights have been cancelled or delayed with further problems expected as more snow is forecast.
Airports including London City, Glasgow and Newcastle have delayed flights to allow them to clear runways of snow. More than 100 flights at Heathrow have been cancelled.
Rural areas have also been cut off with snow flurries blocking roads as well as affecting mobile phone networks.
The forecast from the Met Office, which lasts until 10am on Thursday, said: "Roads will become blocked by deep snow, with many stranded vehicles and passengers.
"Long delays and cancellations on bus, rail and air travel are expected [and] some communities could become cut off for several days."
It also warned of "long interruptions to power supplies and other services".