Passengers desperate to get home for Christmas have been left stranded as Aer Lingus cancelled all flights from Dublin Airport.
The carrier said it had no choice but to suspend departures as it attempts to deal with the knock-on effect of a four-hour closure of runways after earlier snowfall, and plans to run a full schedule on Friday.
Ryanair said it is trying to clear a backlog since all aircraft were grounded until lunchtime on Thursday, but the airline criticised Dublin Airport Authority (DAA) for not clearing the main runway quicker on the busiest travel day of the Christmas period.
Airport chiefs hit back, however, saying staff are currently working around the clock to ensure as many people as possible can get home or away for Christmas.
"We are acutely aware of passengers' frustration, particularly at this time of year, but we have to put their safety and the safety of the crews who fly the aircraft first at all times," said DAA spokeswoman Siobhan Moore.
Elsewhere, Irish Rail, Bus Eireann and Dublin Bus said most services around the country are operating as normal, with some delays and diversions in affected areas. Motorists making the journey home for Christmas have been warned to drive with extreme care as already-sub-zero temperatures plummeted with nightfall making roads treacherous.
Gardai urged drivers to remember that as they leave primary routes conditions on the secondary routes and lesser roads may not be as favourable.
"Extra caution is urged and pre-planning is to be advised. Allow adequate time and check ahead to see what conditions are like local to your destination point," a spokesman added.
Fine Gael road safety spokesman Tom Hayes said there must be increased co-operation between local communities and local authorities during the inclement weather.
He said: "While some authorities have engaged well with local communities, it is essential that there is increased and extended collaboration between the two in all areas. Everyone must work together during this time to get on top of what's to be done and to ensure that our roads and pathways are kept clear and that accidents are kept to a minimum."