Police have urged motorists to take care after Storm Bert arrived in Northern Ireland.
A yellow weather warning for wind, rain and snow is in place for much of Saturday.
There are already reports of several road closures this morning.
Met Office Chief Meteorologist Jason Kelly said: “Storm Bert started to arrive overnight on Friday and into Saturday, initially over Northern Ireland.
“As we go through the first part of Saturday morning, it will start to show its hand across Scotland, north Wales and northern England, with the potential for some heavy snowfall, especially over higher ground.”
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In Northern Ireland, wind and rain is already causing disruption with fallen trees and flooding.
On the higher ground the rain is still turning to snow, with reports of very difficult driving conditions, according to Trafficwatch NI.
Roads affected include the Coleraine Mountain Road, Windyhill Road in Limavady, the Glenpark Road, Omagh and the Glenshane Pass.
A fallen tree has led to Dergbrough Road being closed in Co Tyrone, while in Co Down the Belfast Road near Newtownards is partially shut due to a fallen tree and utility lines, as is the Springvale Road.
The Coast Road in Ballygally is also obstructed due to a rock fall.
The PSNI issued a specific warning to drivers in Co Down.
“Motorists are urged to take extra care on a number of roads in the Newtownards area due to the impact of poor weather conditions this morning,” it said.
“There is a fallen tree on the Belfast Road, and there is also a report of a fallen tree on the Springvale Road, between Ballyhalbert and Ballywalter, at its junction with the Inishargie Road. Both lanes are currently blocked as a result of this.”
Watch: Snow arrives in Northern Ireland as temperatures fall below 0