Weather conditions have begun to improve slightly in some parts of the country.
Sub-zero temperatures resulted in snow and ice disrupting road traffic particularly in the Midlands, Connacht and Ulster.
Many parts of the country are still in the grip of the first cold snap of the New Year.
Snow has been replaced in many areas by heavy rain and high winds, which has added to the already treacherous road conditions.
Snowfalls ended in Donegal this afternoon but gardaí in Letterkenny said roads in the area - especially secondary roads - are still extremely dangerous.
In Northern Ireland, heavy overnight snow is continuing to cause disruption. Many schools have been closed for the day while delays have been reported at George Best City Airport and Belfast International Airport.
Refuse collections have been suspended and visits to many of Northern Ireland's prisons have also been affected.
Iarnród Éireann says all trains are running to schedule. However, a Ryanair flight from Luton has been diverted to Shannon due to weather conditions at Knock airport.
The Stenaline HSS Stena Explorer 6pm sailing from Dún Laoghaire to Holyhead has been cancelled. Passengers were accommodated on the service from Dublin Port to Holyhead at 9.15pm.
The ESB has reported no problem with the power supply due to the weather.
According to Met Éireann, overnight temperatures will not be as cold as last night. It will be quite windy, with not much ground frost.
