The Met Office has updated its yellow status weather warning of snow and ice for Derry from "low" to "medium".
The initial weather warning was issued on Tuesday morning and applies to all of the North of Ireland.
The warning is valid from 12:05am on Friday December 8 through to 6:00pm on Saturday December 9.
"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," read the warning on the Met Office website.
"Two to five 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.
"Possible travel delays on roads stranding some vehicles and passengers with possible delays and cancellations to rail and air travel.
"Some rural communities could be cut off and power supplies interrupted.
"Probably some icy stretches on some untreated roads, pavements and cycle paths. Some injuries from slips and falls on icy and snowy surfaces.
"This warning has been updated to increase the impact level from low to medium."