The forecaster added: "Saturday will be cloudy at first but good sunny spells will develop in the east and north during the day".
The cold blast - dubbed the "Beast from the East" will see temperatures plummeting to minus 8C (17.6F) in places.
But it will turn cold under the clear skies with lowest temperatures falling to between -2° and +1° with a widespread sharp frost.
Meanwhile, night-time temperatures on Saturday and Sunday are predicted drop sharply under clear skies, leading to widespread hard frost and unsafe icy conditions for many.
"However, colder conditions are expected to extend westwards across England during the weekend bringing a significant, and prolonged period of wintry weather".
"Some areas next week will see daytime temperatures hover around or slightly below freezing".
Cold with highest temperatures of 6 to 8 degrees in a moderate southeast wind.More news: Rachel McAdams Is "At Least Seven Months Pregnant" With Baby No. 1
Monday is forecast to be mainly dry, with some sunny spells and the odd snow flurry in eastern areas.
A yellow weather warning for the south east has been issued for 4pm on Monday and remains in place until just 11.55pm on Tuesday.
Saturday is looking to be the coldest day of 2018 so far.
"There is the potential for locally five to 10cm of snow across eastern parts however where showers become more organised there may be more widespread snow cover".
Very cold, with brisk winds and overnight frosts.
For the rest of the week, temperatures will remain cold but will rise above freezing for the rest of the week. This could fall as snow or sleet.