Parts of the country have been blanketed in a layer of snow as forecasters warned of plunging temperatures and possible travel disruption.
Frequent wintry showers have pushed in overnight with the Met Office issuing yellow warnings for snow and ice across much of Scotland and Northern Ireland, The Press Association reports.
Dozens of schools closed in Highlands and Dumfries and Galloway after the overnight snowfall.
On social media, people shared pictures and video of the snow and the disruption.
In areas which saw snow, temperatures dropped to between 0C-2C (32F-36F). Tulloch Bridge in Scotland, had the largest snowfall with 8cm coming down overnight.
Gritters are out in force across Scotland with pictures on social media showing particularly difficult driving conditions on the M8 near Easterhouse.
The southern uplands of Scotland, northern England and Northern Ireland have also seen flurries of snow, with 1cm reported in Lough Fea, Northern Ireland, and further accumulations expected throughout the day.
Luke Miall, a forecaster at the Met Office, said: “The forecast for today is it’s likely to become a bit more wintry so we could be seeing snow for many areas, with northern and western areas seeing frequent showers.”
There is a greater chance of snow further south across parts of Wales and the possibly the Midlands later into Tuesday, forecasters said.
A snow and ice warning is in place for these areas, with 2cm-6cm of snow expected over the hills and 1cm-2cm in lower levels.
Mr Miall added: “It will stay cold, we will continue to feel that wind from the north west, quite gusty, so feeling bitterly cold outside today.
“There could well be some travel disruptions and, with slippery roads and pavements, there could be some treacherous conditions to contend with, so we would advise people to take extra care.”
After the snow and ice of Tuesday, showers are expected to continue into the night with wintry showers on Wednesday, especially across the north.