Today will be the busiest day for travel before Christmas, with airports bracing themselves for arrival and departure of more than 100,000 passengers.
Road conditions may be difficult later this evening as Met Éireann is predicting a very cold and windy night, with heavy rain or sleet showers.
Frequent showers of hail and snow are expected tomorrow, so both the AA and the Garda Síochána have advised motorists to drive carefully and to keep a safe distance from the car in front.
More than 67,000 people are expected to travel in and out of Dublin Airport today. Passengers will be greeted by festive music while airport staff are singing carols around the terminal buildings to raise funds for children's charities.
Passengers have been advised to give themselves extra time to get to the airport, because of the expected road traffic congestion.
More than 75,000 people will pass through Cork Airport during the Christmas period - a 4 per cent increase on last year's figure. Shannon Airport will process more than 85,000 passengers during the same period.
Today is also expected to be the busiest on the roads, with the exodus out of Dublin and other cities expected to begin in the early afternoon.
Mr Conor Faughnan, the Automobile Association spokesman, said the traffic leaving Dublin was expected to start to build up from lunch-time onwards, on roads such as the N11, N7, N4 and N6.
"We find that the pattern at Christmas is similar to a Bank Holiday weekend.
"There will be no major rush- hour, but traffic will build from the early afternoon.
"Christmas Eve is a slightly surreal kind of day because the roads will be quite busy in the morning, but by lunch-time most people are well on their way."
Mr Faughnan said there would not be any major obstacles on the main roads out of Dublin as the repair of the bridge at Rathcoole on the Naas Road had finished ahead of schedule.
"That was a very pleasant surprise and should help traffic," he said.
Last-minute shoppers would keep the traffic busy in city centre areas and around the out-of-town shopping centres, Mr Faughnan added.
Iarnród Éireann and Bus Éireann are expecting large numbers of passengers this evening and tomorrow morning.
Iarnród Éireann will carry up to 400,000 passengers in the coming days, while Bus Éireann expects to have carried 200,000 passengers between tomorrow and January 3rd.
Both companies have encouraged people intending to travel to check the updated timetables at bus and rail stations as there will be are some changes to services, particularly on Christmas Eve.
