Some regions are set to feel colder than the Arctic Circle as “exceptional” freezing temperatures continue into the week ahead.
The Met Office has issued amber snow warnings for north-east, central and south-east England on Tuesday, and eastern Scotland on Wednesday.
An amber warning means an increased likelihood of bad weather causing “road and rail closures, interruption to power and the potential risk to life and property”.
The Met Office said: “Travel delays on roads are likely, stranding some vehicles and passengers. Some delays and cancellations to rail and air travel are likely.
“There is a good chance that some rural communities could become cut off. Power cuts are likely and other services, such as mobile phones, may be affected.”
Public Health England said people should prepare for a “significant and prolonged period of wintry weather”.
Dr Thomas Waite, of the body’s extreme events team said: “Cold temperatures, indoors and out, pose real health risks to many and every winter we know that thousands of people get ill and even die following exposure to cold conditions.
“As forecasters tell us next week temperatures will fall, it’s critical that if you know anyone over 65, with young children or who has heart or lung conditions, that you keep an eye on them and think what help they may need. Staying warm by heating your home to at least 18°C can be crucial to stay well.”
The majority of Britain is facing delays on the roads, trains and in the air by the middle of the week.
Arctic blast hits UK – in pictures
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Several rail operators warned passengers to expect disruption.
Greater Anglia (GA) said it was limiting its services from Monday in anticipation of the snowy blast.
The company said it planned to halt its Monday night train services at 10pm due to the forecast of sub-zero temperatures and large amounts of snow. A limited service will run on Tuesday.
Southeastern urged passengers to finish their journeys before 6pm on Monday to avoid potential disruption, while Southern warned of “major disruption” to its services due to expected snow and icy conditions.
Transport for London (TfL) told 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.
Lows of -5C (23F) recorded over the weekend marked the lowest temperature in the week leading up to 1 March since 1986.
The wind chill, which could see parts of the UK feeling as cold as -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.
Met Office meteorologist Charlie Powell said: “The UK is on track for some really cold weather this week. It’s not going to be record-breaking, but it’ll be pretty exceptional – winds are going to make it feel minus 10C (14F) to minus 15C (5F) during the day.
“We will see the first signs of that tonight in the shape of snow showers working all the way down the east coast.
“That continues into Monday, with snow showers moving across the country during the day before reaching Wales.
“Winds are then going to strengthen and we could see some easterly gales through the eastern Channel and east Anglia by the middle of the week.
“That’s going to make it feel really cold, daytime temperatures on Wednesday and Thursday will be struggling to get above freezing for most of the country.”
He added: “By Thursday evening, there are growing signs there could be some significant snowfall across southern England.
“Unusually for Britain, the snow is going to be quite dry, so it will blow around and gather in drifts and we could see some blizzard conditions.
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