Forecasters are predicting that the wintry weather will continue over the weekend and into next week, with higher ground worst affected.
Drivers are being urged to exercise caution on roads, while prospective air passengers should be aware of the potential for disruption - particularly regarding flights within the UK and Ireland.
England, Scotland and particularly Wales - where a rare red alert is in place - have been hard hit by the ongoing snowy conditions.
An alert has also been issued by Met Éireann in the Republic of Ireland, warning that transport services may be adversely affected.
At Belfast International Airport, a spokesperson said: "The airport remains open and operational - however, we are keeping a close eye on the weather and our snow teams remain on standby.
"Flight delays and cancellations are due to weather at other UK airports.
"Passengers who are due to travel should contact their airline for the latest flight information."
Flights coming from Bristol and London are among the worst affected.
The runway at George Best Belfast City Airport has now reopened after snow clearance procedures. The airport also warned of flight delays and cancellations.
According to forecasters, rain and sleet will turn increasingly to snow as Friday progresses, with the heaviest falls occurring during the evening and overnight.
Snow could turn showery again on Saturday, but further rain, sleet and snow is predicted for Sunday, Monday and Tuesday.
Temperatures will also remain very cold - staying in and around freezing and feeling more like -6C.
On Friday, some parts of Co Down were affected by power outages due to the snow and strong winds.
Northern Ireland Electricity has confirmed that around 2,400 homes remained without power on Friday night, as engineers continued to work to restore supplies.
"The damage is concentrated in the Eastern areas," an NIE spokeswoman said.
"NIE emergency crews are responding to damage and restoring supplies to those affected by the severe weather. "
Customers without electricity supply are advised to contact NIE's Customer Helpline on 08457 643 643.
Areas affected include Bangor, Downpatrick, Rathfriland, Hillsborough, Ballynahinch and Dromara.