The Met Office has issued a red alert weather warning for parts of south Wales and the south west of England as Storm Emma meets the "Beast from the East".

The national weather service's alert stretches from north of Cardiff to south of Exeter.

It will last from 3pm on Thursday to 2am on Friday.

It states: "A spell of heavy snow and blizzard conditions were expected.

"The snow will be accompanied by very strong easterly winds leading to severe drifting. Some places could also see significant ice build up due to freezing rain from later on Thursday evening, most likely in the south of the area.

"Long delays and cancellations of public transport seem highly likely. Some roads are likely to become blocked by deep snow, stranding vehicles and passengers. Long interruptions to power supplies and other utilities are very likely to occur, along with damage to trees and other structures due to heavy snow or ice."

Arctic blast hits UK – in pictures Show all 51 1 /51 Arctic blast hits UK – in pictures Arctic blast hits UK – in pictures Members of the Serpentine Swimming Club brave the icy depths of the Serpentine in Hyde Park Rob Pinney/LNP Arctic blast hits UK – in pictures A person crosses the snowy street in Edinburgh's Royal Mile PA Arctic blast hits UK – in pictures St Michael's Mount, near Marazion, Cornwall, lies covered in snow PA Wire/PA Images Arctic blast hits UK – in pictures Edinburgh's Princes Street in the snow Getty Images Arctic blast hits UK – in pictures Houses covered in snow Penzance, Cornwall PA Wire/PA Images Arctic blast hits UK – in pictures Canal boats are frozen into Birmingham's canal system PA Arctic blast hits UK – in pictures The M62 near Huddersfield was closed for hours on Thursday. A Highways England vehicle set alight PA Arctic blast hits UK – in pictures The M80 near Glasgow was stationary for hours on Wednesday night PA Arctic blast hits UK – in pictures A family make their way in the snow in Balloch, Scotland Getty Arctic blast hits UK – in pictures Closed barriers at Paddington in West London as trains were cancelled from the station AFP/Getty Arctic blast hits UK – in pictures Workers clear a platform at Paddington station in west London AFP/Getty Arctic blast hits UK – in pictures A council worker breaks the ice on the fountain in Trafalgar Square in London Reuters Arctic blast hits UK – in pictures A 4x4 makes its way along the road in Alexandria, Scotland Getty Arctic blast hits UK – in pictures Two boys play in the snow on a housing estate in Alexandria, Scotland Getty Arctic blast hits UK – in pictures The M876 to Glasgow is closed due to snow as storm Emma, rolling in from the Atlantic, looks poised to meet the Beast from the East’s chilly Russia air PA Arctic blast hits UK – in pictures Icicles form on the seafront railings at Penzance in Cornwall PA Arctic blast hits UK – in pictures The British Waterways building in Nottingham PA Arctic blast hits UK – in pictures Snow lingers on rooftops of houses in Newlyn near Penzance, ahead of the arrival of Storm Emma Getty Arctic blast hits UK – in pictures A commuter in a hi-viz jacket cycles through the snow Getty Images Arctic blast hits UK – in pictures A taxi crosses London Bridge AFP/Getty Arctic blast hits UK – in pictures A pedestrian walks along Whitehall in London. EPA Arctic blast hits UK – in pictures A woman feeds the birds in Kensington Gardens AP Arctic blast hits UK – in pictures Snow ploughs clear drifts on the sea front road in Whitley Bay, North Tyneside. PA Arctic blast hits UK – in pictures Vehicles slow in the snowy conditions. AP Arctic blast hits UK – in pictures Icicles hang from a frozen elephant fountain in Colchester. Getty Images Arctic blast hits UK – in pictures A young man takes a running jump down a snow covered hill with his sledge. Getty Arctic blast hits UK – in pictures People help push a car that got stuck in the snow in Rochester. Getty Arctic blast hits UK – in pictures Stationary traffic on the M20 near Ashford. PA Arctic blast hits UK – in pictures A Eurostar train passes through Ashford. PA Arctic blast hits UK – in pictures People use their sleds in the snow in Jackson's Fields in Rochester. Getty Arctic blast hits UK – in pictures Parents walk their children to school in Ashford, Kent, as heavy snowfall is affecting roads across the UK. PA Arctic blast hits UK – in pictures Cars travel through Great Chart in Ashford, Kent. PA Arctic blast hits UK – in pictures Vehicles crawl along a road as snow falls in south east England, as seen through the window of a train travelling from London to Canterbury. AP Arctic blast hits UK – in pictures People walk in the snow in the village of Brenchley in southeast England. AFP/Getty Arctic blast hits UK – in pictures A swimmer braves the snowy conditions at King Edwards bay near Tynemouth. PA Arctic blast hits UK – in pictures A woman scrapes ice from her car. Getty Images Arctic blast hits UK – in pictures People sled in the snow in Rochester. Getty Arctic blast hits UK – in pictures Children play on sledges outside Rochester Castle. Getty Arctic blast hits UK – in pictures Toby Stanton walks to school in Ashford during heavy snowfall. PA Arctic blast hits UK – in pictures Snow stands by parked trains at Ashford International in southeast England. AP Arctic blast hits UK – in pictures A snowy Tynemouth beach, following heavy overnight snowfall. PA Arctic blast hits UK – in pictures Roads across the UK have seen a blanketing of snow, with police forces reporting treacherous driving conditions and blocked routes. PA Arctic blast hits UK – in pictures Commuters face a miserable journey to work as the snow falls in freezing temperatures in Pimlico. Rex Features Arctic blast hits UK – in pictures People photograph a frozen waterfall near Pen y Fan mountain on Brecon Beacon National Park, Wales. PA Arctic blast hits UK – in pictures A woman laden with shopping struggles through the snow in south London. EPA/FACUNDO ARRIZABALAGA Arctic blast hits UK – in pictures Commuters walking in the snow on London Bridge. PA Arctic blast hits UK – in pictures A woman carrying an umbrella walks past a homeless person sleeping in a doorway during a snow shower in London. Getty Arctic blast hits UK – in pictures People make their way through a snow flurry in London. Reuters Arctic blast hits UK – in pictures Trucks are stuck after heavy snow on the motorway in Briscous, near Bayonne, southwestern France AP Arctic blast hits UK – in pictures A commuter pedals along Whitehall in central London EPA Arctic blast hits UK – in pictures A man places snow chains on his tyres in Leek, Staffordshire Reuters

The Met Office definition of its highest level of alert is that "you should take action now to keep yourself and others safe from the impact of the weather.

"Widespread damage, travel and power disruption and risk to life is likely. You must avoid dangerous areas and follow the advice of the emergency services and local authorities".

In their assessment, the Met Office's chief forecaster said: "Widespread snow is expected to develop through Thursday afternoon and evening.

"Around 10-20 cm is likely to fall widely, with the potential for up to 30 to 50 cm over parts of Dartmoor, Exmoor and parts of southeast Wales.

"Snowfall will be accompanied by strong to gale easterly winds, leading to severe drifting of lying snow especially in upland areas. Severe cold and wind chill will compound the dangerous conditions, with very poor visibility.

"Towards midnight, there is a chance of snow turning to freezing rain in places, mainly across the south of the area, with widespread icy stretches making driving conditions particularly dangerous."

People walking in the snow by Tower Bridge in London, as the highest level of weather warning has been issued for parts of England and Wales (Victoria Jones/PA Wire) (PA)

In Ireland, where a red weather alert is also in place, people are being advised to stay indoors to sit out the worst of the blizzards sweeping the British Isles.

Storm Emma, which is rolling in from the Atlantic, looks likely to meet the "Beast from the East's" chilly Russian air, causing further snowfall and bitter temperatures.

Temperatures plunged to a widespread low of between minus 6C (21F) and minus 4C (25F) overnight, and forecasters have warned it could feel as chilly as minus 11C (52F) during the day as the winds continue to strengthen.

As well as the red alert - which has never before been issued for Scotland, England or Northern Ireland - 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.