Extra traffic is expected on the country's roads today - the first Monday in September.
Schools are now back and the majority of people are back to work.
Thousands will also be making their way home from the Electric Picnic festival this morning.
Conor Faughnan, director of consumer affairs for the AA, said: "I would advise everybody just to allow plenty of additional time for the journey.
"If you're coming back from the Picnic and you're not under time pressure, you probably would be better off waiting until mid-morning, because the morning rush hour, on the first Monday in September, is likely to be busy, especially on the Naas Road, approaching the M50."