Travellers are being warned of further disruption, with weather warnings issued for Friday evening and overnight.
The Met Office yellow warnings for snow and ice cover several areas of the UK, while a separate warning for ice is in place for southern England.
Hundreds of schools across Wales and southern parts of England were closed for the day due to the conditions.
The airport advised passengers to check flight information with their airline but said they expected a normal service on Saturday.
Flight disruption at airports in Cardiff and Bristol affected rugby fans heading to Paris ahead of Friday evening’s France v Wales Six Nations opener, with ex-Wales captain Sam Warburton among those caught up in the chaos.
Some Eurostar services were also cancelled on Friday .
Meanwhile, the Met Office has warned of “treacherous driving conditions” in some southern areas.
Highways England warned of delays on the M3, A303 and A34 in Hampshire and Wiltshire because of “challenging” weather conditions.
It said there was only one lane open from J6 to J7 on the M3 westbound near Basingstoke due to multiple stranded vehicles.
Salt-spreaders covered 80,000 miles of England’s motorways and major A roads through Thursday night to keep traffic moving, Highways England said.
On the trains, Transport for Wales said services were now running as normal after some disruption in the morning, while Great Western Railway – which earlier warned of disruption until 12:00 – said a near-normal service had resumed.
Port Vale v Tranmere Rovers was the first of the weekend’s English League fixtures to be postponed because of a frozen pitch, while five Scottish League One and Two matches were also postponed.
Several of Saturday’s matches will be subject to pitch inspections in the morning but fans heading for matches can check for the latest updates on postponements on the
BBC Sport website
In East Ham, east London, a baby girl was found abandoned in a shopping bag in park in near-freezing temperatures on Thursday evening.
Ovidijus Zvaliauskas found the baby with his mother, who was walking her dog.
He told BBC News it was so cold the baby had frost on her head. “There’s no words for it. It’s terrible,” he said.
The newborn girl was taken to hospital and is said to be in a stable condition. Medical staff have been calling her Roman, as the play area she was found was situated just off Roman Road.
South-west England was worst affected on Thursday night, with snow depths of 12cm (5in) recorded in Bodmin, the Met Office said.
Parts of Cumbria saw 8cm of snow, while there was 7cm recorded in Inverness-shire and 5cm in Powys.
Temperatures fell to their lowest level this winter, with Braemar, Aberdeenshire, dropping to -15.4C (6F) in the early hours of Friday.
This is the lowest in the UK since 2012 – when temperatures fell to -15.6C in Holbeach, Lincolnshire.
The cold start to the day saw hundreds of school closures in different parts of the UK. More than 500 schools were shut in Wales, with about 200 in Berkshire, 250 in Wiltshire and 300 in Buckinghamshire also closed.
What’s the forecast?
Wintry showers will continue for eastern areas and northern Scotland into the evening with light rain or sleet expected in south-east England.
Travel disruption is likely throughout Friday and into Saturday due to lying snow and ice.
It will remain cold on Saturday but wintry showers will become increasingly confined to the eastern coast of the UK, leaving some spells of sunshine.
What warnings are in place?
There are yellow warnings for snow and ice covering northern Scotland, most of Northern Ireland, the eastern coast of England and the west coast of Wales until 12:00 GMT on Saturday.
They warn of some snow showers, with heavier accumulations of up to 5cm possible in northern Scotland and up to 10cm over higher ground.
There is also a yellow warning for snow, covering parts of south-east England, between 16:00 GMT and 20:00 GMT on Friday, with accumulations of 2-3cm likely and up to 7cm possible over higher ground.
A separate warning for ice is in place for southern England until 11:00 GMT on Saturday, as Friday’s snow gradually eases during the evening.
Yellow warnings are issued for low level impacts including some disruption to travel. People should check the latest forecast and check how they might be impacted.
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