More than half a million people will be on the move this bank holiday weekend by plane, road and rail.
Aer Rianta is expecting its busiest period ever, with 2,000 flights arriving and departing from the Republic's three main airports over the weekend carrying 375,000 passengers.
Bus Éireann expects to carry more than 100,000 passengers on Expressway and provincial services between today and next Tuesday.
Normal weekday timetables apply today and tomorrow. On Sunday and Monday normal Sunday timetables will be in operation, with some cancellations.
Because of expected delays today and Monday, commuters are advised to travel as early in the day as possible and to allow additional time if making connections between routes.
Almost 200,000 people are expected to travel across Iarnrod Éireann's InterCity network over the weekend. Extra services are being laid on for those travelling to the All-Ireland football and hurling championship fixtures in Dublin and Thurles.
On Saturday, Clare play Kilkenny in the hurling semi-final replay in Thurles. Additional carriages will be put on the 1.30 p.m. regular service from Ennis to Thurles. An extra return service planned to leave Thurles at 6.20 p.m. will be put back until 6.45 p.m. if the match runs in to overtime.
A special service for Roscommon fans travelling to Croke Park to support their county in the football championship qualifiers on Sunday will leave Claremorris at 9.20 a.m and will return from Dublin's Heuston station after the game at 6.20 p.m.
Dart passengers are reminded that normal services resume on Dublin's southside from Saturday after the €80 million upgrade of the line between Pearse Station and Greystones.
However, work will now begin on the refurbishment of the northside line from Pearse to Howth/Malahide. Feeder buses will be laid on from Saturday to replace the rail services at weekends, for passengers using the northside Dart and the northern commuter line.
National Safety Council chairman Mr Eddie Shaw urged motorists to slow down over the bank holiday weekend. Five people lost their lives during the same weekend last year in four fatal crashes.
Garda Superintendent Declan O'Brien from the Garda National Traffic Bureau said officers would be manning checkpoints at accident blackspots around the country in a bid to cut down on speeding, drunk driving and the non-wearing of seat belts.
"This bank holiday weekend we don't want any more deaths. We do not want to be knocking on the door of your family home with heartbreaking news," he added.
The weather looks set to improve, with sunny spells and warm weather forecast for most of the country - good news for the thousands of people attending festivals and sporting events all over the country during the weekend.
It's a busy weekend for GAA fans with Clare, Kilkenny, Roscommon, Dublin, Tyrone and Laois all in action. Traffic around Semple Stadium will be heavy on Saturday and around Croke Park on Sunday.
The Mitchelstown Music Festival kicks off tonight and runs until Monday. Featured artists include Kool & the Gang, the Commmitments and Jerry Fish and the Mudbug Club.
Dublin's Temple Bar will resound to the sound of Latin beats and sounds over the weekend during the Latin Quarter Festival. This celebration of Latin American music features a line-up of world music events, carnival-style street acts and a Latin House DJ trail.
The Spraoi Festival will take over the city of Waterford from tonight until Monday transforming it into a gigantic, free street party with music and street theatre.
The Sligo Festival of the Arts will be hosting the Abbey's touring production of The Playboy of the Western Worldon Saturday at 8.30 p.m.