The AA is recommending that extra time should be factored into road journeys this weekend as delays and heavy traffic from mid-afternoon today are unavoidable on all major routes.
Those going by public transport should bear in mind that upgrade works will start south of Connolly Station. This means there will be no Dart services operating south of Connolly Station over the weekend.
For those heading further afield, the Dublin Airport Authority (DAA) said more than 2,000 flights will be arriving and leaving from the airport between Friday and Monday. More than 310,000 people are expected to travel pass through over the June bank holiday.
With queues up to 25 minutes predicted at the security checks, the DAA said people should arrive at the airport at least 90 minutes before their departure time.
There are a number of events across the State, organised to coincide with the holiday.
Some 30,000 people are expected in Kilkenny this weekend for the Smithwick's Cat Laughs Comedy Festival. The festival, which features 44 comedy acts from Ireland and abroad, kicked off on Wednesday and will run until Monday.
As well as increased traffic in the city approach roads are expected to be congested - including the N9, N76 and N78.
Areas of Newcastle West town centre are closed on Sunday June 5th for the Fleadh Cheoil, and diversions are signposted.
The week-long BudRising festival continues in Dublin with 23 indoor and outdoor events featuring over 130 acts. Check the programme for localised traffic hotspots, www.budrising.ie.
Also in Dublin the Women’s Mini Marathon 2005 takes place on Monday, June 6th. The race will start on Merrion Square at 3pm and will go from Lower Mount Street in a 10-kilometre loop to Stephens Green. Some 40,000 women are expected to take part, and the streets will be closed off for most of the afternoon.
Other sporting activity sees a Leinster Senior Football double header at Croke Park on Sunday. Carlow v Wexford kicks off at 2.30pm, and the clash between Dublin and Meath is a 4.05pm. As usual there are will be restrictions around the stadium.
The World Cup qualifier between Ireland and Israel at 7.30pm tomorrow night will cause delays around Landsdowne Road.
Up to 30,000 people are expected to attend the Munster Hurling Semi Final, Tipperary v Clare, at the Gaelic Grounds on the Ennis Road on Sunday, with kick-off at 2.15pm. Major congestion is likely and there will be traffic restrictions in the area.
Racing takes place at Tramore this evening, starting at 5:25pm, and there is expected to be heavy volumes on the Tramore Road from 4:30pm. Portlaoise will see increased traffic all weekend as the Irish Senior Open is taking place at the Heritage Golf Club.