Icy conditions with overnight double-digit sub zero temperatures in exposed parts of the UK could last for at least a week, the Met Office has said.
The forecaster extended Wednesday’s yellow weather warnings into Thursday and Friday, with ice in coastal and northern England, with both snow and ice expected in northern Scotland.
Arctic air, dubbed the Troll of Trondheim, will quickly move south during Wednesday, leaving most of the country in its grip by Thursday morning.
Met Office spokesman Grahame Madge said: “We are in this pattern for seven days at least.
“We could see it continue for a while longer, there’s uncertainty in the evolution and how long it will last.
“However, the pattern for the next seven days is that it will remain cold and we will see double digit minus figures overnight in areas that are prone to frosts and areas where there is lying snow.”
There was no expectation of widespread heavy snow, but wintry showers were expected during the cold spell, particularly on higher ground and by the coast, Mr Madge said.
Cold air from the north tended to contain less moisture than from the west, meaning less cloud cover and therefore lower overnight temperatures.
Mr Madge said although this will be a cold snap, it will not be as tough as the “hard December” of 2010.
Meanwhile, a major incident was declared in Sheffield after around 2,000 homes in the suburb of Stannington were left without gas for five days, with overnight temperatures plummeting.
More than 100 engineers were working on the problem caused when a burst water main damaged a gas pipe on Friday, sending hundreds of thousands of litres of water into the gas network.
Nationally, Age UK advised people to maintain a supply of food and medicine to reduce the number of outdoor trips and torches with spare batteries in case of a power cut.
Homeless people in London will be sheltered after the Severe Weather Emergency Protocol was activated for the first time this winter to provide emergency accommodation for rough sleepers.