The Met Office yellow weather warnings have been extended to Friday, as parts of the country wake up to snow and ice.
The cold conditions were expected this week as an Arctic blast makes its way down the UK.
More than 10cm of snow fell in parts of northern Scotland on Monday – with the Met Office warning 20cm could fall later in the week.
The cold snap is bringing snow, ice, wind and rain.
Parts of the country have already been hit with snow
The latest alert has added to the warnings already in place for Scotland and northern England, which have already seen snowfall.
Tuesday could be the coldest night of the year so far with the mercury plunging to -15C in some isolated parts of Scottish.
People in southern England and South Wales can expect to wake up to snow on Wednesday but it is unclear whether it will settle, the Met Office has said.
Snow is more likely to settle when it moves across much of northern England, Northern Ireland and much of Scotland on Thursday.
The Met Office has issued further yellow weather warnings
The yellow weather warning in place is advising of national travel disruption and power cuts.
Met Office meteorologist Alex Burkill said people should “expect to wake up to snow” on Wednesday if they live in the South.
He said: “I think over higher grounds such as Exmoor, the Chilterns and the Cotswolds there will be a fair amount of snow.
“Elsewhere it is going to be quite difficult, especially after today’s wet weather, to say how much snow will settle.”
The Met Office are advising to only travel if essential
Burkill warned people to travel in snowy conditions only if essential and to bring a blanket in case they get stuck overnight.
He said: “Through the worst of the weather, keep up to date with warnings, be prepared your journey may take longer than normal and you may end up stranded in your car.
“If there is significant snow take water and maybe a blanket just in case, that’s if you absolutely need to travel.
“Treat the weather sensibly and be aware it could be dangerous.”
Northern parts of England and Scotland have already seen snowfall
The UK Health Security Agency has issued a level-three cold weather alert for the whole of England which is likely to be reviewed in the coming days.
The agency’s head of extreme events and health protection Dr Agostinho Sousa said people should check on vulnerable relatives and told pensioners and anyone with an underlying health condition to heat their home to at least 18C.