Commuters and people returning home for Christmas continue to have their travel plans disrupted as the bad weather throughout Europe shows no signs of easing.
Met Éireann has warned of more snow, particularly in the coastal counties of Leinster, and more freezing temperatures in the coming days.
Chief forecaster Gerald Flemming said a thaw was not now expected until at least Christmas Day.
Dublin airport has suspended all flights until at least 8am tomorrow following heavy snowfalls in the area. Flights are being diverted to Cork, Shannon and Belfast airports, which are operational.
A spokeswoman for the Dublin Airport Authority advised all passengers to consult their airline's websites before travelling to the airport.
Ryanair advised the Dublin Airport Authority that customers with flights booked before 8am tomorrow should not travel to the airport but should instead rebook flights through their website. It advised passengers who are booked to fly from 8am onwards not to travel to the airport unless they have confirmed reservations.
A spokeswoman for Aer Lingus said the airline was at an advanced stage of hiring in extra aircraft to accommodate passengers in coming days. She advised intending passengers to check the airline's website.
"We are going to do all possible to put on extra flights to get passengers home for Christmas," she said, adding that, after the airport opens tomorrow the airline would be running their normal schedule and that additional flights would be put on where availability of aircraft allows.
She said passengers who had had flights cancelled should rebook over the internet where the extra flights would become available over coming days.
Some flights have been cancelled at Knock or diverted to other airports. Kerry, Galway, Sligo, Donegal and Waterford regional airports remain open. City of Derry airport has been shut due to freezing fog.
Gardaí have repeated their advice to motorists not to travel unless strictly necessary and to keep to main roads and daylight travel where possible. Up to 20cm of snow was reported to have fallen in Ballina, Co Mayo today.
In Co Wicklow, the town of Arklow is without electricity following a blackout which occurred at about 5pm
Northern Ireland has one of its coldest nights on record with temperatures falling to minus 17 in Katesbridge, Co Down. An overnight temperature of minus 17.2 degrees was recorded at Straide, Co Mayo. This was a record low for December, Met Éireann forecaster Gerald Fleming said.
Mr Fleming said localised snow showers last night dumped some 10 to 15 cm in parts of south Dublin, while areas on the city’s northside recorded falls of only 1-2 cm. This snowfall forced Dublin airport to suspend all flights for over five hours and caused traffic chaos across the city.
Mr Fleming said there was a risk of further snow showers until tomorrow evening, with the midwest, southwest and east coast regions most at risk. These showers were unlikely to be as intense as those that hit the country last night and this morning and should become fewer in number over time.
He said conditions would remain cold on Thursday and Friday, but that it would be far drier with less of a chance of snow. He said conditions would become significantly milder on Christmas Day and that this should continue on St Stephen’s Day and thereafter.
AA Roadwatch said there was heavy traffic on all routes. Full details are available on aaroadwatch.ie. The M50 is extremely icy in both directions and motorists are advised to drive with extreme care. There are reports of major traffic problems in Santry, north Dublin, with large numbers of motorists abandoning their cars.
Dublin Bus said the last buses from both the city centre and suburbs will depart at 10pm. Nitelink services will not run tonight.
A full list of the routes affected is available on dublinbus.ie and passengers can also telephone the Dublin Bus customer information line on 01-8734222.
The majority of Bus Éireann services are operating as normal, though some delays and diversions may be expected. Bus Éireann said this evening its last services would depart at 9pm.
The Luas red and green lines are operating as normal and Iarnród Éireann said full services are operating throughout its Intercity, Dart and Commuter routes although some delays may occur to facilitate the clearing of points. There are reports of delays on some routes.
Some filling stations in northwest Donegal have been forced to ration petrol and diesel. Garages in Gweedore and Gortahork, had been forced to limit customers to just €20 of fuel each. Many garages had run very low on fuel after treacherous roads prevented delivery trucks from Derry from making the journey.
All Irish Sea ferries were operating as normal today.
The National Roads Authority said there were sufficient salt supplies with about 6,000 tonnes in reserve nationally and that a fresh shipment of salt would arrive in Cork tomorrow. It said some 25,000 tonnes would be available to service roads over Christmas.
As schools continue to be affected, groups representing teachers, principals and boards of management have called for a review of the national school calendar to give schools flexibility to make up lost days. The Irish Primary Principals Network said that if schools can make up the lost days, then they should.
The Defence Forces are continuing to transport medical staff and patients across the country today. Troops are also assisting with snow clearance in Co Meath. Last night, the Air Corps used specialised night vision goggles in difficult weather conditions to fly a young patient from Cork to Dublin for treatment.