Strong winds from Storm Gertrude brought several trees down and damaged electricity lines across Northern Ireland, causing widespread power cuts.
NIE Networks said its repair crews have restored supply to 18,000 customers but it is still working on faults affecting about 250 homes and businesses.
The worst affected areas were counties Tyrone, Londonderry and Antrim. The strongest wind recorded was 85mph.
Helicopter patrols surveyed the electricity network for damage.
Earlier, NIE Networks said it would help to identify broken power lines in rural areas, so repair crews could be sent directly to the damaged equipment.
On Friday evening, a number of roads across Northern Ireland remained closed due to fallen trees and flooding.
In Armoy, County Antrim, trees at the Dark Hedges, made famous by the HBO series Game of Thrones, have collapsed onto the Bregagh Road.
In Maghera, County Londonderry, a tree fell on a car on the Mullagh Road.
The driver, a man, suffered minor cuts and bruises but was able to walk away from his vehicle.
In County Tyrone, firefighters rescued a pet rabbit from a roof after its hutch was sent "airborne" by strong winds.
NIE Networks emergency crews and engineers are working to restore power to the remaining customers and it opened its main incident centre in Craigavon, County Armagh, to co-ordinate its response.
The firm said working conditions were difficult on Friday morning as crews replaced broken poles, clear trees and reconnected overhead power lines in blustery winds.
NIE Networks communications manager, Julia Carson, said the restoration effort had been in operation "as soon as the storm struck".
"We were in regular contact with the Met Office and had mobilised NIE Networks emergency crews, engineers and call handlers in preparation for any damage the severe weather may cause," she said.
"We have already restored power to thousands customers and are continuing to assess the damage and carry out repairs."
Ms Carson also advised the public: "Put safety first and if you do see any trees down across power lines or broken electricity poles, keep away and call NIE Networks immediately."
Electricity customers who have lost supply in Northern Ireland should call NIE Networks' customer helpline on 03457 643 643 or report the fault online using their website: nienetworks.co.uk
There is a yellow warning of wind and snow for Northern Ireland until 18:00 GMT on Saturday.
Storm Gertrude has also caused damage in Scotland and the Republic of Ireland overnight.
The Irish state broadcaster RTÉ said more than 2,000 homes and businesses in the Republic of Ireland were without power on Friday evening after severe winds.
County Donegal is the area worst affected.