Nearly every part of the country was hit by snowfall and gales as the Met Office said Thursday was the UK's coldest spring day on record.
Forecasters are warning of life-threatening conditions and said winter "is still in control" as Storm Emma arrived with the country already in the grip of Siberian cold air nicknamed the Beast from the East.
The death toll from the storms rose to 10 after a seven-year-old girl died whilst playing in the snow in Cornwall when a car hit a house.
More than 1,000 schools were closed during disruption which is being described as the worst "in a generation", and hospitals cancelled non-urgent operations and appointments.
Panic-buying and snowbound delivery lorries left supermarket shelves empty of food in some parts of the country.
Theresa May has been forced to move her long-awaited Brexit speech from Newcastle to London, while households are being urged to "carry on cooking" after the National Grid issued a "gas deficit warning", prompting fears of a shortage.
The Environment Agency activated five coastal flood warnings urging the public to take 'immediate action', with two in Cornwall, one at Swanage in Dorset, and others for the Tyne Estuary and one for the North Sea at Whitley Bay.
Sixteen further flood alerts have been issued telling people to 'be prepared' across South West and North East England due to strong winds combined with high tides.
Road conditions remain dangerous with motorists across much of the UK warned against driving unless absolutely essential.
The AA said ยฃ10 million worth of damage has been done to cars in just three days with an estimated 8,000 collisions, two thirds of them due to snow and ice.
In Hampshire, police declared a "major incident" on Thursday night as motorists were stranded for several hours on the A31.
The force said they were unable to move the vehicles off the carriageway for "at least the next few hours", but were working to evacuate the most vulnerable people from the scene.
Police said they were also carrying out a "rescue operation" to help people stranded in their vehicles across Somerset, including about 100 vehicles stuck in snow on the A303 at Ilminster.
In Greater Manchester, dozens of volunteers have been battling through snow to take supplies to people stranded on the M62 motorway. Police say wind speeds over the Rakewood Viaduct in Greater Manchester have reached 90mph.
Eleanor Kelly, 19, said local residents in Milnrow, Rochdale, had been taking hot drinks, food and blankets to those stuck on the carriageway - including to a father with a baby and toddler in the car.
The South Central Ambulance Service NHS Foundation Trust, which provides services in Buckinghamshire, Oxfordshire, Berkshire and Hampshire, has appealed for help from 4x4 owners to move its staff around in the adverse conditions.
In Scotland, First Minister Nicola Sturgeon criticised transport company bosses who had continued to send drivers out on to the roads despite official warnings to avoid non-essential journeys.
Army and Royal Air Force personnel were called in to ferry health workers through blocked roads in Lincolnshire and in Scotland. Ten RAF 4x4 vehicles with 20 airmen began transporting health staff from dawn in Lincolnshire after an urgent request from local police.
Soldiers from 3rd Bn The Rifles and 2nd Bn The Royal Regiment of Scotland transported staff from Edinburgh Royal Infirmary and the Western General.
Gavin Williamson, the Defence Secretary, said: "Our service personnel are showing great dedication and a spirited sense of duty as they support local authorities and keep the British people safe."
Meanwhile energy minister Claire Perry was forced to try and downplay the National Grid's gas deficit warning, as she told people: "Do carry on using your gas heating and cooking meals as normal."
An unusual red weather warning, the second in 24 hours, was issued for south-west England and south Wales as Storm Emma moved in with strong winds, "blizzard conditions" and "severe drifting". The warning, valid until the early hours of Friday, is just the third issued in seven years and means "widespread damage, travel and power disruption and risk to life is likely". Some parts of the south west could see up to 50cm (1ft 8in) of snow.
Met Office forecaster Sophie Yeomans said: "Things could yet get worse, there is more snow on its way. The problem will be when the snow gets trodden down and compacted and turns to ice.
"Meteorologically, it's the first day of spring but winter is clinging on and giving us a right old kicking.
"It's still in control."
A woman was forced to give birth on the storm-battered A66 near Darlington when she became stranded in terrible conditions.
Sienna Waring was delivered by her father Andrew as he tried to get her mother Daniella to hospital. She was born near Stockton-on-Tees moments before paramedics arrived at the scene.
Mr Waring, from Catterick, North Yorkshire, said: "Having been present at the birth of our two other children, I just copied what I had seen then.
"I opened the passenger door and knelt in the snow."
Thursday's low temperatures set a record for the UK's coldest spring day. In Tredegar in Wales, the mercury never got above -5.2C, beating the previous record low of -4.6C at Cassley in Sutherland, Scotland, on March 2 2001.
Nearly all train operators warned of cancellations and disruption and all cross-border trains between England and Scotland were suspended.
Virgin Trains East Coast asked passengers "not to travel" today or tomorrow across the entire East Coast Main Line between London and Scotland.
London Paddington, the UK's seventh busiest station, was closed for several hours from 8am, meaning long distance services had to start and terminate at Reading.
Hundreds of flights were also cancelled.
As well as the red alerts, amber warnings have also been issued for the north-east of England and the central belt of Scotland, in place between 10am and 8pm on Thursday, and for south west England and south Wales from 12pm until 8am on Friday.
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.
The prolonged cold spell will collide with Storm Emma, which is hitting southern and western parts of the UK. Blizzards, strong winds and travel disruption are predicted for southern, western and central England, as well as parts of Wales and Northern Ireland.
Temperatures plunged to a widespread low of between -6C (21F) and -4C (25F) overnight, and forecasters have warned it could feel as cold as -11C (12.2F) during the day as the winds continue to strengthen. Gusts of up to 60mph could also bring "blizzard-like conditions".
Storm Emma, which wreaked havoc in Spain and Portugal before moving up over the Atlantic, is expected to dump up to 50cm (15in) of snow by Friday.
"If you don't have to go anywhere over the next few days, stay at home," warned Met Office forecaster Simon Partridge.
The storm, a band of low pressure, will mix with freezing temperatures and strong winds brought to Britain by the "Beast from the East".
As the storm hits, there is a chance of freezing rain and black ice, adding to the already dangerous driving conditions.
Several sports fixtures have been disrupted by the weather conditions including the postponement of four Super League rugby league games and the Premier League Darts in Exeter being cancelled.
Seven-year-old girl dies in collision in Cornwall
Devon and Cornwall police confirmed that a seven-year-old girl died in Looe, Cornwall.
In a statement the police said: "Police were called at around 2.30pm today to reports of a Nissan car colliding with a house on Bodrigan Road.
"A seven-year-old girl, believed to be a pedestrian, suffered life-threatening injuries and was declared deceased at the scene.
"Her next of kin has been informed. Localised closures area in place as emergency services attend this incident."
Elsewhere a 75-year-old woman has been found dead in a snowy street in Leeds. She was found partially hidden beneath a car in the Farsley area of the city.
Royal Air Force drafted in to help relief efforts
The Royal Air Force (RAF) has been drafted in to help relief efforts in snow-hit Lincolnshire, with 10 4x4 vehicles and some 20 staff aiding emergency services.
A Ministry of Defence spokesman said: "The RAF is assisting in helping to transport health staff to hospitals and support health workers in visiting vulnerable people in the community in Lincolnshire following heavy snowfall.
"There are three UK standby battalions held at high readiness to respond to UK contingencies and emergencies, including support to local authorities.
"We have the right people with the right training to respond to a range of contingencies."
National Grid warns of gas supply shortage
The National Grid has issued a "gas deficit warning", as fears mount that supplies could run empty amid extreme weather conditions across Britain.
The power operator said the warning has been issued in response to a series of "significant supply losses resulting in a forecast end-of-day supply deficit".
Household supplies are not expected to be affected, but shortages could hit industrial users as the Grid attempts to balance supply and demand into Friday.
It plans to do this by limiting industrial use and buying in more gas if necessary. According to the National Grid's forecast, there is a shortfall of around 50 million cubic metres. It said in a statement:
"National gas demand today is high and due to the extreme weather conditions, there have been gas supply losses overnight."We are in communication with industry partners and are closely monitoring the situation."
"At 5.45am this morning we issued a 'Gas Deficit Warning' to the market.
"This is an indication to the market that we'd like more gas to be made available to ensure the safe and reliable operation of the national gas network.
The stark warning came as snowfall brought parts of Britain to a standstill, trapping motorists on roads and threatening air, rail and road journeys across the country.
Roads, rail and air travel - latest updates
Severe weather has caused another day of travel disruption on the roads, to flights and to trains. Travellers were urged to check the latest situation before setting off on their journeys. Here are some of the latest reported issues:
Roads
In Scotland, 300 motorists remained stuck on the M80. Around 1,000 were there overnight as heavy snow fell.
The motorway was closed southbound between junctions 8 and 9.
Police Scotland warned people not to travel unless they were an emergency worker.
Lincolnshire Police warned overnight that the A52 was "impassable" between Boston and Skegness due to drifting snow, and warned that drivers faced becoming stranded.
"We are not in a position to recover you," the force tweeted.
The fire and rescue service added that even a snowplough was unable to get through to clear the route.
Several other roads in Lincolnshire have also been shut, including the A17 and the A15 between the M180 and Lincoln.
Cheshire Police said there were around eight miles of tailbacks on the M62 as officers with 4x4s, Highways England patrols, contractors and snowploughs attempted to clear snow between junctions 21 and 22 eastbound.
By 8.30am on Thursday morning the AA said it had already answered calls from more than 100 drivers stuck in snow, with East Anglia and the North East the worst-hit regions.
AA president Edmund King compared driving on many "atrocious" UK roads to skating on ice rinks, and said they had added extra patrols and 4x4s to cope with the severe conditions.
The A66 in Cumbria was closed in both directions between Scotch Corner and Brough, due to "severe snowfall", while the A56 in Lancashire was likely to be closed for "several hours" due to a lorry crash between the M65 and A680.
Highways England said the A1 remained closed in both directions glasgbetween the A192 and the Scottish border and shared images on Twitter of lorries stranded in the snow on the stretch of road.
Northumbria Police said the A68 was closed between Corbridge and Ridsdale. In Derbyshire, the Woodhead Pass was shut in both directions between Tintwistle and Flouch.
One person was taken to hospital after a crash involving 16 vehicles on the M66 southbound between the Ramsbottom and Bury junction.
Greater Manchester Fire and Rescue Service (GMFRS) said two fire engines and an off-road vehicle were sent to the scene at 11.25am.
Trains
Nearly all train operators across the UK are suffering cancellations and disruption on Thursday.
All cross-border trains between England and Scotland were suspended.
The West Coast Main Line was closed until at least midday between Carlisle and Scotland, with no trains or replacement buses.
Virgin Trains East Coast asked passengers "not to travel" on Thursday or Friday across the entire East Coast Main Line between London and Scotland.
ScotRail halted all operations in the affected red area until late morning.
London Paddington, the UK's seventh busiest station, was closed at 8am. Long distance services are starting and terminating at Reading.
Around 50 stations in Kent and East Sussex were closed on Thursday as operator Southeastern advised commuters to work from home if possible.
Northern said the severe weather had left several routes blocked, with delays and cancellations across the whole network.
Flights
Airports have been severely affected by the conditions, with hundreds of flights cancelled.
Heathrow was badly hit, with airlines forced to reduce schedules on Thursday and Friday following discussions with airport officials and air traffic control provider Nats.
British Airways cancelled more than 180 flights, affecting long haul and short haul routes.
Other airlines to cancel flights at the west London hub include Virgin Atlantic, Lufthansa and Flybe.
A total of at least 76 flights serving London City Airport were cancelled on Thursday.
Glasgow Airport announced it will remain shut for the second day in a row due to heavy snow.
The closure had originally been expected to last until 11am on Thursday, which was then extended until 3pm. However, continuing extreme conditions have forced the airport to close for the rest of the day.
Edinburgh Airport tweeted that most airlines had cancelled services until lunchtime. There were also cancellations and delays at Gatwick Airport.
The runway at East Midlands Airport was temporarily closed on Thursday morning, and travellers were warned it could affect flights.
Ryanair said it has cancelled all flights to and from the following airports for the rest of Thursday: East Midlands, Leeds Bradford, Edinburgh, Glasgow, Cork and Kerry. The low cost airline also cancelled a number of flights serving Dublin Airport.
Here are the number of flights cancelled at some airports in the UK and across Europe, according to flight data website Flightradar24:
- Dublin: 194
- Heathrow: 157
- Edinburgh: 129
- Glasgow: 105
- Geneva: 96
- Gatwick: 77
- Amsterdam: 69
- London City: 67
- Bristol: 48
- Charles de Gaulle (Paris): 41
"If their flight is in the European Union or their airline is an EU carrier, customers will be entitled to food, refreshment and overnight accommodation or a refund of proportionate costs and will be flown home as soon as is possible at their airline's expense."
Comment: UK: 20,000 homes without water as record cold bursts pipes testing ill-prepared infrastructure
Honeymoon couple heading for Maldives among hundreds stranded in airport
A newlywed couple are having an unexpected honeymoon - stranded in Glasgow Airport amid the wild weather.
Chris and Vicky Robinson, from Stranraer, got married last weekend and were looking forward to a luxury holiday in the Maldives when heavy snow closed the airport on Wednesday.
Instead of enjoying 30C heat in the Indian Ocean, they spent the night in chairs in Glasgow Airport's main terminal - catching a few hours sleep as they waited for news on a rescheduled departure.
Mr Robinson, 29, said: "We were about to board the plane yesterday at 1pm, and 15 minutes before we were to take off they cancelled it and we've been here since (in the terminal), slept here with a lack of information through the night.
"It was very subdued, people were quiet and a bit confused because there wasn't much information. We'd heard about camp beds and blankets, but we got no information about that.
"There's been more information this morning, I know it's been tricky for (the airport) because of maybe a lack of workers and it's difficult for everyone."
Mrs Robinson, 27, said she had shed a few tears on Wednesday.
"If we don't get away by tonight then we'll probably not go because it's only a week we're going for and it's too far to go for any less than that really," she said.
"There was tears to start with but there's not much you can do. We had the perfect wedding so you can't ask for everything.
"My suitcase isn't going to work out for this weather in Glasgow for a week so we might need to go home."
The airport said it has faced an unprecedented weather situation. Many staff also stayed at the airport overnight to help with the situation, and runway teams have been working since Tuesday night to try to clear flight paths.
Drivers stuck for up to 13 hours as good samaritans hand out food
Extreme weather and jack-knifed lorries combined to cause "significant challenges" on one of Scotland's main roads where motorists were stranded overnight.
Deputy First Minister John Swinney said there had been an "extensive operation" taking place to try to get traffic on the M80 motorway - which links Glasgow and Stirling - moving again.
Motorists reported being stuck for up to 13 hours, with some spending the night in their cars, and others abandoning their vehicles on the motorway.
Emergency responders and volunteer agencies, including mountain rescue teams, checked on stranded drivers, with some good samaritans also handing out food.
Mr Swinney told BBC Radio Scotland the country was experiencing "the most significant snow incident we've had since 2010". And he said the M80 had been a "particular pinch point" after traffic ground to a halt.
Speaking on the Good Morning Scotland programme, the Deputy First Minister said: "The M80 has presented much more significant challenges to us overnight and there has been a very strong operation to try to gain traction over the course of the night.
"Although many people were stuck for a long time we did get the road moving quite significantly, but there are people who have been stuck there for a long time.
"That's a combination of the intensity of the snow, but also the fact that we have had quite a number of jack-knifed lorries on that particular stretch of the road and the minute that happens the road gets blocked and nobody can get through."
He said the "overwhelming majority" of Scots had heeded warnings to stay at home.
"Many people have responded to those warnings very significantly but we do face challenges at particular pinch points, and the M80 has been our most difficult situation to try to manage," he said.
"I assure members of the public there has been an extensive operation in place to try to maintain traction on that road and to get motorists on the move as quickly as possible."
He also stressed people should stay at home today unless they are essential workers.
A&E departments face 'perfect storm'
A "perfect storm" of appalling weather, persistently high hospital admissions due to flu and a renewed spike in norovirus put accident and emergency departments under considerable pressure last week, with the prolonged cold conditions set to put them under even more strain.
NHS England warned that the current bout of freezing weather could increase health risks for vulnerable patients such as the very young, very old or those with chronic diseases.
Dr Nick Scriven, president of the Society for Acute Medicine, said the severe weather is an "added burden on top of the recent 'usual' winter" and hospitals are likely to be forced to cancel routine procedures.
He added: "Today and the next few days will particularly stretch trusts, with staff struggling to get to work and ambulance trusts having immense problems getting patients to and from hospital.
"A lot of hospitals will cancel routine work over the next few days as a consequence of both of these. Overall NHS staff are pulling together and making immense efforts to keep people our hospitals safe."
The latest data shows more than 12,300 patients had to wait longer than 30 minutes to be seen after arriving at A&E units in ambulances last week, with more than 2,870 patients having to wait more than an hour, both down on the week before.
'What dedication!' NHS staff camp out on wards to defy snow - and surgeon walks eight miles for cancer operation
NHS staff who slept in wards to ensure patient services could continue despite the weather have been praised by the public.
Medical staff stayed overnight at Sunderland Royal Hospital, while others who were brought in by 4x4 volunteer drivers will do so on Thursday night into Friday.
When the City Hospitals Sunderland NHS Foundation Trust posted a message about its staff and asked for the public to thank them, more than 20,000 people "liked" it.
And the page was flooded with messages of gratitude. One person wrote: "What dedication! The NHS wouldn't run without people like you all."
Paediatric nurse Lisa Gerrett, 38, from County Durham, was brought in to work by a volunteer driver in a 4x4 and will stay over at the hospital so she can work on Friday.
The mother of four said: "I am on shift today and tomorrow and even if I could get home tonight, I would still have to manage to get in again in the morning, and I'd be relying on another 4x4 driver.
"If I stay, it means the driver can collect other nurses. It also means I can cover for night staff who cannot get in, if necessary."
Staff at Sunderland Royal Hospital were praised by the public and fellow medics alike:
Meanwhile, it has emerged that a Glasgow surgeon walked for eight miles in the snow to operate on a cancer patient.
The unnamed medic walked from Anniesland to Paisley so she could get to work on Thursday morning.
Her colleague, Glasgow-based colorectal surgeon Andy Renwick, told BBC Radio Scotland: "I won't give her name because she would be genuinely upset with me.
"She walked from Anniesland to Paisley - it took her two hours and 50 minutes. I saw her come in, she had snow goggles on, Gortexed up, top and bottom, snow shoes and walking poles.
"She is operating today on someone who has bowel cancer, she knew that had to be done and so she has made extra effort to get in here to make sure that was actually delivered."
Record number of rough sleeper alerts
A record number of homeless alerts have been sent to a major charity. More than 3,600 alerts were sent to the app StreetLink, which connects the homeless to local services, between Monday and Tuesday morning - the highest total ever for a 24-hour period.
This app allows concerned pedestrians to alert local authorities about people sleeping rough in the cold weather.
Around 500 extra beds in shelters, hostels and churches have been made available in the capital through local authorities, charities, faith and community groups after a Swep (Severe Weather Emergency Protocol) plan was triggered.
In response to the bitter conditions, St Mungo's homeless charity and the City of London have opened a new emergency shelter - in the Guild Church of Saint Mary Aldermary - which took in seven people on its first night.
St Mungo's has said London is experiencing its most prolonged period of freezing conditions for seven years, which could prove deadly for people sleeping outside.
Petra Salva, director of London's rough sleeper services, said that deaths on the streets over the bitterly cold snap were "a horrific possibility".
She said: "If we don't act, then people could die and... we don't know yet what the consequences of this prolonged cold weather has been."
She said her mouth had "dropped open" after she walked into the church and saw a homeless person her team have been working with for four years, who, until now, had not accepted offers of a bed inside.
She said: "If tonight, he was the only one who came in, it would make it worthwhile."
How to help rough sleepers in cold weather
Councils across the country have implemented Severe Weather Emergency Protocols for rough sleepers, meaning if passers-by report concerns to their local authority, they will send someone from the Rough Sleeper Team to help.
Check with the local council for individual contact details or speak to Streetlink.
This is also activated across London, meaning local authorities have a duty to offer emergency shelter to any rough sleepers.
Streetlink has asked concerned pedestrians to report the time, place and appearance of anyone sleeping rough in these temperatures.
A volunteer will then seek out the rough sleeper and offer them a warm bed for the night.
Either download their app or contact them online using the link above or call their 24-hour hotline on 0300 500 0914.
World Book Day costumes wasted as schools closed
Parents who toiled over making costumes for their children have spoken of their dismay as the snow meant many World Book Day events were cancelled across the country, reports Helena Horton.
Some schools remained open, but called off the dressing-up event because they feared pupils would get too cold in their fancy dress outfits.
Others have closed and some parents said they were worried the effort that had gone into the costumes was wasted.
But some parents let their children dress up in their costumes anyway during their "snow days" at home, setting up activities at home such as themed painting.
Conditions to worsen as ice set to form on snow
The extreme weather shows no sign of letting up, with fears snow in the south west could turn into freezing rain on Friday - making conditions "even more treacherous".
Heading into Friday the snow in the south west might turn into freezing rain and could give a glaze of ice on top any lying snow - making conditions even more treacherous.
The Met Office said the highest temperature in the UK on Wednesday was 1.7C (35F) recorded in Katesbridge, County Down and the coldest in Braemar, Aberdeenshire at -5.3C (22F).
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."
Man dies after being pulled from icy lake
The Metropolitan Police named the man who died after being pulled from the water at Danson Park, near Welling, south east London on Wednesday, as Stephen Cavanagh.
A statement said: "In respect of the death of a man following an incident in Danson Park, Bexley on Wednesday, 28 February, the deceased has been formally identified as Stephen Cavanagh, 60, who lived locally.
"The family of Mr Cavanagh have requested that they are not contacted by the media at this difficult time. We ask the media to please respect their wishes."
Elsewhere, a young boy had a lucky escape when he was rescued from a frozen lake.
Firefighters rescued the youngster, who tried to run to the middle of a frozen lake and got trapped when the ice broke up at Laindon near Basildon, Essex on Wednesday afternoon
He was said to have been cold but otherwise unhurt.
Dozens die in freezing European weather
Fresh heavy snowfalls and icy blizzards are also expected to continue lashing large swatches of Europe as the continent shivers in a deadly deep-freeze that has gripped countries from the far north to the Mediterranean south.
Schools are shut and weather agencies predict the brutal cold will continue as the death toll from the freezing snap rose to around 48 since last Friday, with icy conditions causing accidents and endangering vulnerable rough sleepers.
The victims also include 18 people killed in Poland, six in the Czech Republic, five in Lithuania, four each in France and Slovakia, two each in Italy, Serbia, Romania and Slovenia and one in Spain.
The BIG SECRET no one, especially in government, is talking about.
Now you know why WW3 is being orchestrated....to cull the masses under more-or-less controlled conditions before panic and chaos ensues as life on planet earth becomes...IMPOSSIBLE.
The Age of Warmth is over and the Age of Ice is beginning.