With more heavy snow expected overnight, the PSNI have warned motorists to avoid the road network.
Treacherous road conditions have resulted in multiple closures while many other roads are proving impassable due to snow, fallen trees and stranded vehicles.
The Roads Service said north-eastern parts remained badly affected, with additional external contractor resources drafted in on Friday night to assist in clearing roads.
Earlier, a blackout left around 200,000 homes and businesses temporarily without power in the Belfast area.
Northern Ireland Electricity said it was the first time in decades that an outage of this scale had occurred in the city.
The power cut, which lasted up to one hour in some places, was caused by a major fault on the transmission network.
"NIE engineers are investigating," a statement read.
Electricity has been restored to all customers affected by the fault, which happened at around 7.30pm.
Around 40,000 homes and businesses remain without electricity across Northern Ireland after storm-force winds of up to 55mph and heavy snow damaged the electricity network.
Cable icing and trees bringing down lines and breaking poles led to the worst power cuts NIE say they have seen in 15 years.
The damage is concentrated in south and eastern areas of the region, and also parts of the North Coast.
The company says the clean-up could take two days, and the areas worst affected by power outages are counties Antrim and Down.
An amber weather warning for snow remained in place for counties Antrim, Armagh and Down on Friday night.
Heavy snow accumulations have been recorded, particularly in the north east of the region, with drifting of up to 40cms.
The Met Office says further significant snow accumulations are likely on hills on Saturday, with continued drifting and blizzard conditions in the strong southeasterly winds.
The very cold and wintry weather will continue with snow showers on Sunday although dying out on Monday and Tuesday.
Julia Carson, NIE Communications Manager, said: "The restoration process has been steady throughout the day and we are working to restore the customers as quickly and safely as possible.
"However, the atrocious weather conditions have made access very difficult and the high winds, combined with snow and icing, are still causing damage to the network," she added.
"The severe weather is set to continue through tonight and into tomorrow and we are likely to see further damage to network which will affect electricity supplies.
"Due to the particular weather conditions customers may notice brief dips in their lights on a regular basis. We would ask that customers do not phone in to report these dips and only contact us if their electricity is completely off.
"We are doing everything we can to get everyone back on supply as quickly and safely as possible, and have brought in additional emergency crews from ESB in the Republic of Ireland."
Power has been restored to over 100,000 homes and businesses since the severe weather began in the early hours of Friday.
The public should be prepared for the possibility of severe disruption, particularly to transport and to power supplies.
MET office spokesperson
The Northern Ireland Ambulance Service says it is also experiencing delays in responding to an already high number of emergency calls.
A spokesperson said calls are being responded to but delays are inevitable and may continue for up to 36 hours.
"In order to ensure that those most seriously ill or injured patients receive the most timely response, NIAS would ask the public to call 999 only when absolutely necessary for the duration of this period of bad weather," they said.
Around 100 schools were closed across Northern Ireland on Friday, while transport has been badly disrupted.
Belfast City Airport closed early on Friday evening due to the adverse weather conditions.
"We would advise all our passengers to contact their airlines before travelling to the airport tomorrow for an update on their flight status," a statement read.
"The airport will endeavour to operate from 06.30am as normal tomorrow and will be providing all updates where necessary on the status of the runway here on the website or on our social media pages, facebook and twitter.
"We would like to thank all our passengers for their patience today."
Belfast International Airport is operational, but with significant delays to flights. Passengers are advised to check with their airline for the latest information.
A spokesperson said staff have been working "continuously to ensure the airport remains open".
"We have had three cancellations, taken three diversions from Belfast City airport. We have had some significant delays to flights but we are working hard to ensure passengers can get flights."
Translink say they have experienced some delays across all services due to the weather conditions.
Elsewhere, the Larne half-marathon, which was due to take place on Saturday morning, has been postponed as a result of the weather. A new date will be released soon.
If you are affected by power outages, NIE says the latest information will be left via recorded messages.
Customers are asked to listen fully to the recorded telephone messages which will provide the best and latest information available. If possible, customers will be answered by a call handler; otherwise there will be a separate facility to leave a message to report visible damage to the electricity network such as broken poles or lines. Customers can also report a fault online. Customers who have lost supply are advised to first find out if their neighbours are also without power and check household fuses and trip switches before contacting NIE.