Summer has begun in earnest with thousands taking to the roads for the bank holiday weekend.
The usual exodus from the east coast to the south and west of the Republic is predicted to cause delays. AA Roadwatch says motorists should expect heavy traffic in and around major towns and cities.
Spokesman Conor Faughnan said the May bank holiday heralds the start of summer for many and gardaí will be targeting the busy roads with increased levels of enforcement, primarily focused on speeding.
The Dublin Airport Authority (DAA) said it expected 208,000 people to travel through the airport over the three days. Among them will be thousands of Leinster and Munster rugby fans travelling to this weekend's Heineken Cup semi-finals in France and Spain.
DAA spokeswoman Siobhán Moore said bookings were down on previous years because of the recession but the airport would be busier than on normal weekends.
"Regardless of whether you're checking in online or at the airport, people should present themselves at the terminal building at least 90 minutes before departure time to give themselves time to clear security and get to the boarding gate," she said.
Temperatures across the State will remain cool for the time of year due to persistent northerly breezes, says Met Éireann. Forecaster Eoin Sherlock described the outlook for the weekend as a "mixed bag", with showers and thunder storms likely in some parts today.
Tomorrow and Monday will be brighter and drier, with average temperatures ranging from 10 to 14 degrees, he said.
The weekend's events kick off in the capital with the inaugural SoGo festival which seeks to tap into the city's cultural and culinary vibe. There will be more than 60 free, or nearly free, events over the three days, mainly in the streets between South Great George's Street and Grafton Street.
In Limerick, the annual Riverfest will include cultural and sporting activities, from fishing to dragon-boat racing. The three-day event also includes a food market on the banks of the river and an open-air céilí.
In Cork the annual All Ireland Strongman contest takes place in the grounds of the Silver Springs Hotel on Monday.
Wallace and Gromit animator Jim Parkyn is the celebrity draw at a three-day modelling workshop in Belfast's Odyssey complex. More than 18,000 people are expected to take part in city's marathon which starts at 9am outside city hall on Monday.
The Kilkenny food trail will have delicacies from 38 food producers, restaurants and local culinary businesses. And Galway hosts a two-day beer brewers festival in Salthill's Oslo Bar.