Forecasters said the freezing temperatures could spark travel chaos and power cuts as Britain is gripped by its coldest February week in five years.
Bitterly cold air from Siberia, nicknamed the Beast from the East, is forecast to envelope the country and bring significant and disruptive snowfall.
The Met Office told the Standard snow was forecast for London and the south-east on Monday, Tuesday, Wednesday, Thursday and Friday this week.
Met Office Meteorologist Alex Burkill said he could not rule out snow falling “pretty much anywhere” in the UK in the coming days.
He warned motorists of potential delays on the M25 during the Monday morning rush hour when the first of the wintry showers is expected.
Mr Burkill said: “Tonight it’s going to be cold again, dropping to -3C or -4C with largely clear skies for much of the night before tomorrow morning when we will see a few snow shower towards the east of London, including eastern parts of the M25.
“We could see some problems for the morning rush hour.”
Mr Burkill said snowfall could be “quite frequent and persistent” on Tuesday, while further wintry showers were expected for Wednesday.
“On Thursday, it will be windy and feel very cold. The temperatures will barely climb above freezing but it will feel as if it is between -5C or -10C,” he added.
“Significant snow is forecast overnight into Friday coming from the South West. A few cm of lying snow is expected for people waking up on Friday morning.”
The Met Office has issued yellow ‘be aware’ warnings for snow for Monday, Tuesday and Wednesday. It is currently considering upgrading Tuesday’s warning to amber and issuing another warning from Thursday night into Friday.
The warnings are in place for London and the south-east, the east of England, the Midlands, the north of England and Scotland.
It has been bitterly cold in the capital this weekend but conditions have been dry and bright with lots of sunshine.
The lowest temperatures in London and the south-east were -1.4C in Iver Water and -2C in Wisley.
The coldest recorded temperature in the UK was -9.2C Altnaharra in northern Scotland.
Health officials have warned of the risks of exposure as temperatures plummet and urged people to look out for the most vulnerable around them.
Dr Thomas Waite, of Public Health England’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.
“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 staying well.”