Motorists in Scotland are being urged to exercise caution as a band of snow moves across the country.
And drivers in the south-west have been urged to “avoid unnecessary journeys” following a spate of road accidents.
Police said heavy snowfall across Dumfries and Galloway was causing problems on roads across the region, including the A75, which is blocked just outside Dumfries.
A Met Office yellow weather warning for snow and ice is in force until 18:00.
In the south-west, the A75 Grenta-Stranraer road is blocked at the Glen, just outside Dumfries, as vehicles are unable to get up the hill.
Heavy snow is also affecting the A76, the A701, the A709 and the A713.
In a statement, police in Dumfries said: “At this time we would advise against making unnecessary journeys. Local authorities are aware and gritters are patrolling.”
Traffic Scotland urged drivers to check their routes before setting off and to ensure they were carrying emergency supplies in case they get stuck.
North Wales Police also warned of poor conditions on the roads due to snow and ice, particularly on routes in Snowdonia.
Meanwhile, the Mountain Road was closed on the Isle of Man due to snow.
In Northern Ireland, a yellow warning of ice was in force until 09:00 on Sunday, while a yellow warning of rain runs until 3pm.
The yellow “be aware” warning covers much of inland Scotland, and was later extended to cover the north-west Highlands and parts of the Western Isles.
Large swathes of England may also be affected, with areas as far south as Hertfordshire, Essex and Suffolk covered by the warning.
BBC Scotland Weather’s Christopher Blanchett said the band of snow, sleet and rain would move north-east across Scotland on Sunday.
“Expect a centimetre or two to low levels; 10cm or more on ground above 300m,” he added.
The Met Office’s chief forecaster said most of the expected snow would fall on higher ground and snowfall would vary considerably across the warning area.
He added that rain could fall on frozen surfaces following a “very cold night”
“Some roads and railways likely to be affected, with longer journey times by road, bus and train services,” the forecaster said.
“Some injuries from slips and falls on icy surfaces. Probably some icy patches on some untreated roads, pavements and cycle paths.
“The snow is expected to become confined to northeast Scotland later in the day as it progressively turns to rain from the southwest.”
Saturday night saw the coldest temperature recorded in the UK since February 14 2016, when minus 14.1C was recorded at Braemar.
Despite the frigid temperatures in the far north, the mercury rose to 11C in the far south west of England.
Met Office forecaster Steven Keate said the near 20C difference, caused as warmer air moves in, was “pretty unusual for the UK”.
“The broad theme is it is turning milder from the west, but before we get there some snow will fall,” he said.
What the weather warning colours mean
- Yellow: Severe weather expected. Yellow means you should plan ahead thinking about possible travel delays, or the disruption of your day-to-day activities.
- Amber: Be prepared for disruption. There is an increased likelihood of bad weather affecting you, which could potentially disrupt your plans and possibly cause travel delays, road and rail closures, interruption to power and the potential risk to life and property.
- Red: Extreme weather is expected. Red means 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.
The latest weather warning follows a week of cold weather, snowfall and travel disruption in Scotland.
It continued on Saturday, as a number of football matches were cancelled, including the Scottish Cup tie between Fraserburgh and Rangers.
The fourth-round tie, due to be played on Sunday, was called off after the pitch at Bellslea Park failed an inspection.
There was also disappointment for some snowsports fans who had hoped to take to the slopes on Saturday.
Many of them got caught in heavy traffic and lengthy tailbacks at Glencoe Mountain Resort and Nevis Range.
Police told motorists queuing to get into the ski centres that the car parks were full and urged them to “turn back”.
And two men were rescued from a mountain ridge in Glencoe after spending the night in sub-zero temperatures.