Snow showers are causing disruption on the roads on Sunday morning as forecasters warn of a frosty start to the half-term holidays.
The wintry weather arrived in parts of western England, western Scotland and Northern Ireland overnight, as the Met Office issued warnings for snow and ice across large swathes of the country.
The North West Motorway Police tweeted there had already been "numerous reports" of accidents on the roads due to the conditions, and urged drivers to slow down.
Frequent and heavy hail and show showers are expected throughout the day, with up to 10cm of snow predicted to fall on higher ground, particularly across western Scotland.
The Met Office has warned of the potential for power cuts, as well as vehicles becoming stranded on the roads.
The weather warnings - which mostly affect the western side of the UK - remain in place until just before midnight on Sunday, although forecasters said further warnings were likely to be put in place over the next two days.
Met Office forecaster Craig Snell said: "It's going to be a very cold day, wherever you are, with temperatures feeling sub-zero in many places.
"Many of us will see at least a few snow showers. You'll need to wrap up warm and make sure you take a bit of extra time, especially in the north west where there will be icy patches forming."
Temperatures will then plummet on Monday, when many children are starting their half-term holiday.
The mercury is predicted to dip below freezing for many parts, with possible lows of minus 5C (23F) in Scotland and a widespread frost in the morning.
More snow is also expected in western parts during the day.
There could be a some respite, however, with milder temperatures set to return mid-week.