Motorists have been told to only drive if necessary in areas covered by the Met Office's amber weather warnings
These alerts are now in force across the UK - with heavy snow expected in a stretch from Stoke-on-Trent to Durham, as well as North Wales and some of Northern Ireland
Significant disruption to transport, power lines and phone network coverage is likely in those places
Parts of central and northern England could see up to 40cm (16in) of snow overnight
The UK recorded its coldest March night since 2010 last night, with -16C (3F) in the Scottish Highlands
Hundreds of schools have been shut in Wales, and more than 250 schools are closed across the West Midlands region
Our weather watchers in Northern Ireland have sent in photos from Belfast and Derry.
Temperatures over there were recorded at -8.7C.
Image source, Colleen McCormack Murtagh, Weather WatcherTwo horses in the snow in Magherafelt, County Derry
Image source, Pete's Portal, Weather WatcherKnock, Belfast
Image source, Annemarie Hughes O'Loughlin, Weather WatcherTwo sheep in the snow in Kilrea, County Derry
Angie Phillips
BBC News NI Weather Presenter
Across Northern Ireland, overnight temperatures were well below freezing in a few places, with Castlederg dipping to -8.7C, its coldest night since 2010.
The cold air looks set to stay with us until the weekend.
An area of low pressure passes to the south of Ireland tomorrow and associated weather fronts will swing in around it from the south bringing wintry showers from Thursday afternoon.
Bristol Airport says it has now reopened but there is still some flight disruption after the heavy snowfall this morning.
Earlier the airport said operations would be suspended until at least 11:00 GMT.
In an update on Twitter, external, the airport says it is now open and operational, but "disruption across airline networks has resulted in some ongoing flight disruption".
People flying from the airport are advised to check the latest flight information with their airline, it adds.
Image source, EPA-EFE/REX/ShutterstockThe Netherlands southernmost province, Limburg has seen heavy snow this morning
The UK isn't the only country in Europe that's waking up to snow this morning, with the Netherlands, Belgium and Denmark also reporting unusually high snowfall for March.
But the wheelie bad weather hasn't stopped these cyclists from taking to their bikes to brave the commute!
Image source, EPA-EFE/REX/ShutterstockA snowy scene in Belgium's capital Brussels is set at the city's Jubilee Arch landmark
Image source, AFPResidents in the 'cycling capital of the world', Denmark's Copenhagen, were ready to ride through the weather
Steven McKenzie
BBC Scotland Highlands and Islands reporter
Image source, Raymond BesantSheep in snow at Scapa in Orkney
Rural communities across the Highlands and Islands are well-acquainted with snow-filled icy blasts this time of year.
Scottish Gaelic even has a phrase for it - sneachd beag nan uan, the small snow of the lambs, and a reference to the weather coming during the busy lambing season on crofts and farms.
For Scotland's mountain ski resorts spring snow brings a much-needed boost to business.
Cairngorm Mountain, near Aviemore, reported having 35cm of powder snow in the space of 24 hours earlier this week, and the Lecht and Glenshee ski centres have also reported fine snow sport conditions under blue skies.
Councils are "ready to work round the clock" according to the Local Government Association (LGA).
As temperatures plummet, it says workers will "grit roads and pavements to make sure that people are kept safe".
The LGA represents 350 councils in England and Wales, which have the responsibility for local road maintenance.
Cllr David Renard, Transport spokesperson for the LGA, said:
“Councils have stockpiled 1.4 million tonnes of salt and are using new and innovative technologies where they can to ensure those areas that are most treacherous are kept clear and safe for use."
Image source, Sean/ Weather watchersA wintry image taken at Brae in Shetland
All schools in Shetland will be closed today due to the continued wintry weather conditions.
More than 20 schools are closed in the Highlands this morning because of the wintry weather conditions.
Fresh snowfall overnight has led to accumulations of lying snow on the roads.
A yellow weather warning for snow and ice remains in place for parts of Scotland today.
Image source, PA MediaThese early morning swimmers took the cold in their stride at King Edward's Bay, near Tynemouth on the north east coast of England
Image source, PA MediaThis jogger took advantage of a quiet Long Walk near Windsor Castle to go for a run earlier
Image source, PA MediaThe Arctic conditions weren't going to stop this bunch celebrating International Women's Day at King Edward's Bay
Image source, PA MediaThese dogwalkers bundled up early this morning for a stroll in Windsor
Image source, Norman/ Weather WatchersSnow lay thickly in Maud, Aberdeenshire
In Scotland the coldest night of the year was also the coldest March night in the UK since 2010.
Speaking on BBC Radio's Good Morning Scotland programme BBC Scotland weather forecaster Joy Dunlop said: "Last night was officially the coldest March night on record in the UK since 2010."
The Met Office warned snow and ice could cause travel disruption in Scotland through to Friday night.
A series of yellow "be aware" warnings have been issued.
The heaviest snowfalls are expected on Friday with the Highlands, Aberdeenshire and central and southern Scotland covered by warnings.
The cold conditions follow Scotland's third-mildest February on record, according to provisional statistics, external.
(This post has been updated to correct an earlier error)
Image source, Getty ImagesWest Burton power plant
Yesterday the National Grid used its reserve coal power units for the first time ever, so extra electricity was available between 16:30 and 20:30 GMT.
Two coal units at West Burton were sync'd into the National Grid during the afternoon and remained online until the evening.
Now, this wasn't the first time reserve coal power was ready to go, but it was the first time it had needed to be used.
You may remember that back in October the energy grid operator warned that some homes could face rolling three hour power cuts if the UK couldn’t secure enough gas and electricity imports.
Having coal plants on standby was one option to try and make sure this did not happen.
As we reported earlier, parts of Scotland experienced the coldest March night since 2010 overnight when the mercury dropped to -15.2C (4.6F) in Kinbrace.
The Met Office has shared an update in the last few minutes saying temperatures at Kinbrace, in the Highlands, have since dropped a little further to -15.4C this morning.
Night-time sub-zero climes are predicted in all four UK nations until at least Friday, with several weather warnings in place.
Marita Moloney
Live reporter
Image source, Getty ImagesMany of us will be waking up to frozen landscapes in the coming days as Arctic weather conditions bring ice and snow across the UK.
It also means we may need to de-ice our cars in the mornings, but it's not just a matter of pouring hot water on the windscreen and driving off.
In fact, this is exactly what you shouldn't do - pouring hot or boiling water on a frozen windscreen will only crack the glass or cause the screen to quickly freeze again.
Instead, the AA says you should turn on your car - ensuring the wipers are off to avoid damage - and then turn on the warm air blower on the windscreen.
You should also turn on your rear windscreen heater, plus the air con to ensure your windows don't fog up. The next step is to then clear any snow with a soft brush, before moving on to using a scraper and de-icer on the car.
The AA also advises motorists to steer clear of any hacks they might have heard of - including using half a potato on the inside windows to stop them steaming up.
As we reported a few minutes ago, Bristol Airport suspended flights this morning as a result of the heavy snowfall.
In a new update, the airport says operations have now been further suspended until 11:00 GMT.
"The Bristol Airport teams are working hard on snow clearing operations, but as the snow continues to fall, flight operations have been suspended until 1100. For the latest flight information please check with your airline," it said in a tweet, external.
Some more advice on how to stay safe in your car in these conditions.
As for the driving itself - use second gear to pull away, if you drive a manual vehicle. Maintain the right speed for the conditions - not too fast so that you risk losing control, but not so slow that you risk losing vital momentum. And leave even more space behind the car in front than you usually would.
If you get stuck, do not try to keep moving if the wheels spin - it will only dig you in deeper. Use a shovel to clear snow from under your tyres. Pour cat litter, sand or gravel in front of the wheels to help get traction.
Image source, .As always, this snowy and icy weather presents challenges and risks for drivers - and in some cases, it could be better for you to avoid the roads altogether. But if you do have to drive, here are some tips:
Prepare yourself by de-icing your car and by planning for journeys to take much longer. Stick to major roads and resist the temptation to take shortcuts on minor roads. And pack appropriately, with warm clothes along with snacks and a hot drink, along with a fully-charged phone and a shovel.
Prepare your car, too - consider buying winter tyres or at least ensuring that standard tyres are fully inflated. Make sure to keep your fuel tank and screenwash topped up - and use antifreeze at the right temperature. Clear all snow and ice from the windscreen, windows and roof before driving off.
Simon King
BBC weather presenter and meteorologist
Snow depths have reached 14cm in Altnaharra in Scotland.
Follow the latest on warnings and the areas affected here.
Snow depths in Scotland have reached 14cm.
Earlier we told you that parts of Scotland had experienced their coldest night of the year.
It turns out that temperatures in the Highlands plummeted as low as -15.2C (4.6F), which the Met Office describes as the coldest March night since 2010.
Forecasters said the record lows in Kinbrace were down to an arctic blast which is being experienced across much of the UK right now.
All schools in Shetland have been shut for the third day in a row due to the wintry weather and there are further closures in Aberdeenshire, external.
Image source, Janis HedleyThree peacocks seen in the snow in Invershin, Scottish Highlands
Marita Moloney
Live reporter
Image source, PA MediaCommuters brave the cold during snow fall at Hitchin train station in Hertfordshire this morning
Several train operators have reported delayed services this morning, with more disruption likely this evening and for the rest of the week as the cold spell lingers.
Southeastern says there is "multiple disruption" across its network this morning.
Southern said commuters could expect "some changes to services" throughout the day, and said people should check their route before travelling with National Rail., external
Network Rail Kent & Sussex said in an update at 08:00: "Snow that fell overnight is impacting a few services this morning. Please check before you travel. More snow is forecast this afternoon with disruption to services expected from 17:00."
Train companies have also urged people to allow plenty of extra time to complete their journey today, including Thameslink who said this morning: "You should also consider alternative routes to reach your destination, or travel later if possible."
Despite Scotland bearing the brunt of the snow today, Scot Rail has not reported significant disruption yet. Similarly, the weather has not affected trains in Northern Ireland.
In Wales, a number of services have been cancelled but this is largely due to more trains than usual needing repairs at the same time.
Bristol Airport has suspended all flights after snow fell across the west of England.
The snowfall has meant disruption to other transport services - especially in Somerset.
Bristol Airport said flights would be suspended until at least 08:00 GMT, with the airport's departure's web page showing that more information on this morning's flights will be released at 09:00.
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Simon King
BBC weather presenter and meteorologist
Image source, BBC Weather Watchers/Bryn CariadChilly times for small paws in Pwll, Carmarthenshire this morning
Heavy snow across southern England and Wales is gradually easing with a mixture of sleet and rain now in the far south.
However, we’ll see another area of rain moving into south-west England which will turn to snow as it spreads into Wales, the Midlands and the south Pennines later on today.
The next area of significant snow will move in later on Thursday and overnight into Friday morning across northern Wales, the North Midlands and northern England which will bring some disruption.
Numerous Met Office weather warnings are in force and some details may change so stay tuned to the forecast.