The Met Office has upgraded its Yellow weather warning for Northern Ireland from 'low' to 'medium'.
The weather warning is expected to be in force between 00.05 on Friday and 6pm on Saturday (December 9).
The updated warning says: "During Friday, increasingly frequent snow showers already affecting northern Scotland and Northern Ireland will extend across many other northern and western parts of the UK.
"2-5 cm of snow is likely fairly widely, with 10-20 cm in places, mainly northern Scotland, Northern Ireland, north Wales and perhaps the northwest Midlands.
"Icy surfaces are also likely to be an additional hazard, especially overnight.
"The heaviest and most frequent snow showers will progressively become confined to northeast Scotland during Saturday.
"Possible travel delays on roads stranding some vehicles and passengers with possible delays and cancellations to rail and air travel."
The Chief Forecaster added: "During winter weather which brings snow showers, it is not uncommon for snow amounts to vary considerably across short distances.
"On Friday and Saturday, the snow showers could lead to snow accumulations which vary markedly across the warning area.
"Strong northwest winds may cause drifting of the snow in places with blizzard conditions possible across northern Scotland."