Motorists have been urged to take extra care in hazardous driving conditions, while health chiefs reminded the public that "cold kills".
People are advised to look out for those who may be vulnerable to the cold, such as the elderly, while the threat of slips, trips and falls on icy surfaces are also underlined.
Heavy snowfall of up to 10cm is forecast in parts, while temperatures are set to plummet below zero.
There are also warnings of severe gales with gusts reaching 70mph on coasts.
Sky News weather producer Chris England said: "We're in a northerly flow at the moment, meaning it's tuning much colder.
"Fairly clear skies over the next few days will lead to extensive overnight frosts, with temperatures widely down to around -6C in the North and -3C in the South on Saturday night.
"Parts of the North, and especially the North East will remain below freezing all day.
"Saturday looks like being the coldest night, but temperatures will slowly recover from the West later, with most places frost free by Thursday."
Dr Angie Bone of Public Health England (PHE) said it was important people took extra care when out and about.
She said: "It's worth remembering that while most outdoor slips, trips and falls in weather like this are of those who are of working age, accidents can happen to anyone.
"Also take some time to think about how the bad weather may affect your friends and family, particularly if they are older or very young or have pre-existing health conditions.
"Although most of our advice on keeping warm and well in cold weather may seem like common sense, it's important to remember that cold kills, even in places where the temperatures aren't at their lowest."
The cold snap has already been causing travel disruption as blizzards swept across parts of the UK leading to road closures.
The Angel of the North in Gateshead saw snow as temperatures struggled to get beyond low single figures in the region.
The A68 was closed in both directions between Errington Arms roundabout and the A6079 junction because of snow, while long delays and hazardous driving conditions were reported on the B6317.
In the Scottish Borders, the local authority urged motorists to "take care on the roads and drive to the conditions".
Further south, snow fell over parts of the Staffordshire Moorlands overnight and in Wales the snow and icy conditions were reportedly affecting the roads.
The A474 in Neath was closed earlier after a car overturned in icy conditions between Cwmgors and Pontardawe.
