Commuters have been warned to expect travel disruption as a snowy blast dubbed "the Beast from the East" hits Britain.
Some parts of the UK are set to feel colder than the Arctic Circle as freezing temperatures continue into the week ahead.
Amber warnings of snow have been issued by the Met Office for north east, central and south eastern England on Tuesday, and eastern Scotland on Wednesday.
It warned of "heavy snow showers", with a spokesman adding: "Travel delays on roads are likely, stranding some vehicles and passengers.
"Some delays and cancellations to rail and air travel are likely."
Rural communities could become cut off, and people could face power cuts and loss of other services, the spokesman added.
Widespread snow is forecast, and the Met Office has issued yellow weather warnings for Monday, Tuesday and Wednesday.
By the middle of the week, the majority of Britain is being warned of the potential for delays on the roads, trains and in the air.
Train operators warn of possible disruption
Greater Anglia (GA) said it was limiting its services from Monday in anticipation of the snowy blast.
An advisory on its website warned that due to the forecast of sub-zero temperatures next week and large amounts of snow, the rail operator planned to halt its Monday night train services at 10pm, with a reduced service from 8pm.
A limited service will run on Tuesday.
South Eastern urged passengers to finish their journeys before 6pm on Monday to avoid potential disruption.
Great Northern has advised passengers to travel as early as possible on Monday evening and will run a heavily-reduced schedule on Tuesday, urging passengers to check their journeys before they travel.
Transport for London (TfL) warned passengers to check ahead of their journeys as disruptions were possible on Underground and Overground services due to the low temperatures forecast.
Train operator C2C also warned of limited services, advising trips after 9pm on Monday could be altered or cancelled, and has warned against all but essential travel on Tuesday
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The wind chill, which could see parts of the UK feeling as cold as minus 15C (5F), rivals the temperatures forecast for parts of northern Norway and Iceland.
The Met Office said that by the end of Wednesday, more than 20cm of snow may have accumulated in some parts of eastern England, Scotland and Northern Ireland.