Winter is "still firmly in charge", a Met Office forecaster has said as Britain prepares for another day of sub-zero temperatures, icy blasts and "blizzard-like conditions".
It comes as Storm Emma, rolling in from the Atlantic, looks poised to meet the Beast from the East's chilly Russia air - causing further widespread snowfall and bitter temperatures.
The Met Office has issued a red alert for Scotland, the highest level of weather warning, that is in place until 10am on Thursday with up to 40cm of the white stuff expected in some areas.
Forecaster Craig Snell said although Thursday marks the first day of meteorological spring, "winter is still firmly in charge across the UK".
He also warned that extreme weather will grip Britain for another 48 hours.
"The red warning is our highest tier, we don't often see a red warning - the last one was back in 2016 up in Shetland and Orkney and that was for strong winds," he said.
"The last time we had the red snow warning was back in 2013 and that was for South Wales - they do not get issued that often."
Mr Snell revealed that a red warning for snow has never before been issued for Scotland, England or Northern Ireland.
Amber snow warnings have also been issued for North East of England and the central belt of Scotland, in place between 10am and 8pm on Thursday.
From 12pm on Thursday until 8am on Friday an amber snow and ice warning has also been issued across south west England and south Wales.
On top of these, yellow snow warnings have been issued for vast swathes of southern, central, and northern England, Northern Ireland and Wales - in place for most of Thursday.
In response to the impending heavy snow showers all schools, community centres and libraries in Edinburgh will be closed, the city's local authority said.
Plymouth Council said more than 80 schools would be closed on Thursday, with more than 50 in Newcastle and 103 across Devon remaining shut.
On top of the Amber snow warning in the south west, Mr Snell said there could be 50 to 60mph winds that will bring "blizzard-like conditions".
"There could be 10cm to 20cm of snow quite widely in that area, with possibly Dartmoor or Exmoor seeing up to 50cm of snow," he added.
Heading into Friday he warned that the snow in the south west may turn into freezing rain and could "give a glaze of ice" on top any lying snow - making conditions "even more treacherous".
On Wednesday as icy blasts gripped Britain, a man in his 60s died after being pulled from a lake in Danson Park, south east London that he had fallen into.
Firefighters also rescued a young boy who had tried to run into the middle of a frozen lake and got trapped as the ice broke up at Laindon near Basildon, Essex.
Disruption across the country's rail and road network is expected to ensue throughout rush hour on Thursday as wintry conditions continue to blight Britain.
Gatwick Airport said due to the severe weather they are "expecting a large number of cancellations and delays to flights".
Advising those travelling to check the status of their flight with their airline, the airport stressed to passengers "not to travel to the airport if it is cancelled".
Edinburgh Airport also tweeted to say most airlines have cancelled their operations had cancelled flights from there until lunchtime on Thursday.
Police across the country also advised motorists to avoid driving if possible owing to poor visibility and treacherous conditions.
The Met Office said the highest temperature in the UK on Wednesday was 1.7C recorded in Katesbridge, County Down and the coldest in Braemar, Aberdeenshire at -5.3C.
Mr Snell warned: "Generally many places on Thursday will struggle to get anywhere near -1C, a few people will come up above, but many of us will be firmly below freezing."