The icy conditions are likely to be caused by a weather phenomenon called a "sudden stratospheric warming" above the North Pole, which will drag very cold air from Siberia to the United Kingdom as early as next week. This freakish weather pattern is thanks to a huge upheaval in the stratosphere.
'As that high pressure builds an easterly flow will start to develop and we will start getting an easterly wind and cold air moving in from Eastern Europe by the time we get to the weekend, ' he said.
Temperatures will begin to drop from Wednesday as sub-zero Siberian winds edge into southern and eastern Britain.
For the most part it will be dry this week, however, we can't rule out very light snow showers developing each day.
"We are looking at a classic beast from the east scenario". It looks likely to be the worst freeze of the winter and could knock the start of spring back well into March.
"The cold easterly wind will bring an element of wind chill which will make it feel colder in the south". High pressure from the west will merge with higher pressure over Scandinavia.
However, they do confirm that Monday and Tuesday will be very cold for the time of year with daytime temperatures in the low single figures inland, and around 5 or 6 degrees on coasts. Overnight frosts expected as temperatures will drop widely below freezing. "However its' looking increasingly likely that we will see colder than average weather over the next week or two".
Dr Thomas Waite, of Public Health England's extreme events team, urged people to check on friends, family and neighbours during the cold snap, and to make sure their homes are heated to at least 18C.