Up to six inches of snow fell in just two hours in some parts of the country as most of the UK was blanketed in white and thousands of schools closed their doors.
In south Wales, where the Met Office issued a rare "red warning" for 30mph winds and a foot of snow, 10,000 households were left without power this morning and 5,000 homes still had not been fixed this afternoon.
Half of those remain in the worst hit west of Wales where heavy snow on the road network is slowing down repair operations.
"We currently have 5,000 customers off supply and are dealing with 70 incidents on our high voltage network, normally we would expect six in 24 hours," a spokeswoman for Western Power said.
"Over half of these incidents and over 3,000 of these customers are in West Wales. The road network is really badly affected and even with 4X4s we are unable to gain access to many locations.
"We have additional crews attempting to travel in from Brecon and helicopters on standby to move staff into the area when it stops snowing."
But the possibility of further incidents is high as low temperatures are set to continue through the weekend.
Hospitals are preparing for a spike in admissions as high numbers of people are injured in falls on icy ground.
Birmingham, Cardiff, Bristol and Southampton Airports were closed for parts of the day.
Heathrow cancelled more than 240 flights and closed one of its runways throughout the morning. Other airports reported disruptions.
More than 400 schools in Hampshire and the Isle of Wight, 300 in Norfolk, 300 in Gloucestershire, 110 in Northamptonshire, 300 across Bedfordshire, Buckinghamshire and Hertfordshire and 1,100 schools in Wales were closed.
Herefordshire, Worcestershire, Warwickshire and Staffordshire were particularly also badly hit - with almost 700 schools across the four counties closed by the early afternoon.
Many major roads including the M4 eastbound between Bristol and Bath and the M50 eastbound in Herefordshire at junction three were closed.
Numerous accidents added to the problems for motorists. Among major routes affected by accidents were the M25 in Hertfordshire, Essex and Surrey; the M4 at Theale in Berkshire; the M3 in Surrey; the M1 in Leicestershire, the M6 and the M54 in Staffordshire and the M62 in West Yorkshire.
The AA said they were dealing with around 900 breakdowns an hour.
Train operators were running revised schedules with one in five trains either delayed or cancelled and Eurostar cut some journeys between London and Brussels.
Commuters faced the possibility of being stranded tonight as all trains out of London's Victoria station were cancelled just before rush hour.
The Met Office warned that the snow that has fallen is here to stay - and there will be more for London and the South East on Sunday.
But as the snow eases across many areas, ice is expected to become the main hazard over the weekend and the Met Office has issued yellow warnings across much of Britain.
The current flurries are expected to ease tonight but the temperatures for most of the country will hover at around zero or -1C.
Forecaster Robin Thwaytes said: "For the weekend it will be mostly dry and pretty cold.
"We have another band coming up from the South East that will push snow across London and East Anglia."
Although the wintry showers will be patchy they could bring another two inches of snow.
Mr Thwaytes added: "The snow is probably going to take a long time to melt, and we don't want it to melt really quickly because we have had such a wet winter, that would bring with it other problems.
"It looks like it will be a slow thaw, probably by next week or the week after."
Merthyr Tydfil was among the worst hit areas in the country today, with reports of panic buying causing some local shops running out of stock.
Council staff in Surrey and Milton Keynes enlisted the help of 4x4 drivers to deliver services to the vulnerable - with Surrey even managing to get 50 farmers with ploughs on board to support its existing highways teams.
The Met Office confirmed that the snow fell across the country largely as predicted - with 30cm in some areas of Wales and four inches across large swathes of the country.
Only Cornwall and areas of Northern Scotland escaped the white-out.
Trains between Bridgend and Cardiff Central were delayed, while there were no services between Radyr and Coryton in South Wales, nor between Liskeard in Cornwall and Plymouth in Devon, nor between Severn Beach and Avonmouth near Bristol.
There were 60-minute hold-ups for passengers on trains between Derby and Birmingham New Street due to a broken-down train at Burton-on-Trent.
Another broken-down train - near Gloucester - led to delays between Gloucester and Newport in South Wales.
As the snow settled quickly around London, the Romford-Upminster rail line was closed due to a train fault.
Train passengers in the centre of the capital faced delays of up to 60 minutes to services through Blackfriars station.
On the Isle of Wight, where old Tube trains operate on the Island Line, all services were suspended until the end of the day.
Delays continued between Bicester North and London due to a lineside equipment problem between High Wycombe and Beaconsfield.
Trains were not stopping at most of the London Overground stations between Watford Junction in Hertfordshire and Queen's Park in North West London.
The NHS has urged elderly people to stock up on supplies and to avoid trips to the shops during the worst of the weather.
Frank Saunders, Met Office Chief Forecaster, said: "Although some further slight snowfalls are likely, with 1 to 2 cm of fresh snow in a few places, the focus switches to ice, with temperatures staying below zero over snow cover for many areas.
"The public should be aware of the risk of localised disruption to transport during this spell of wintry weather."
Steve Crosthwaite, head of the Highways Agency's National Traffic Operations Centre said: "We advise drivers to check road conditions and the Met Office weather forecast before they set off and during severe weather to consider whether their journey is essential. They may want to delay their travel until conditions improve and to allow our winter fleet the chance to treat the roads."