Temperatures are expected to reach 23 degrees in some parts of the country over the next few days.
The south-east is expected to get some of the hottest weather so far this year, while mild conditions are predicted for most of the rest of the country over the bank holiday weekend, according to Met Éireann.
"It will be reasonably mild, and the rainfall will be quite low, but most places may not be all that sunny. There will be a lot of cloud about," a Met Éireann forecaster, Ms Sarah O'Reilly, said.
The nights will be mild and misty, with drizzle, and the mornings generally dull. However, it should brighten up during the afternoons, with sunny spells in most places, except the north-west which is likely to stay dull. Today and tomorrow will have the best weather, while Sunday is expected to be cloudier. On Monday there is a risk of drizzle, but no heavy rain.
Meanwhile the National Safety Council has urged motorists taking to the roads over the weekend to stay within the speed limits.
Huge volumes of traffic are expected today and tomorrow, according to AA Roadwatch. Routes heading south to Kilkenny for the Cat Laughs festival are expected to be busy from early today. A heavy buildup is also likely on the N11 heading south and the N2, N3 and M1 heading north and the N7 to Cork.
The NSC chairman, Mr Eddie Shaw, said yesterday that many drivers believed it was acceptable to drive a few miles per hour over the speed limit. They considered "real speeding" to be in excess of the limit by more than 10 m.p.h., he added. "This is a dangerous attitude as there is no such thing as safe speeding."
Inappropriate and excessive speed is a contributory factor in approximately 40 per cent of fatal crashes in Ireland each year, according to the NSC. This means that speed-related crashes could contribute to the death of about 150 people each year, serious injury to about 600 people and minor injury to more than 3,000.
Even within the speed limits drivers need to ensure they drive at appropriate speeds, Mr Shaw said.
Iarnród Éireann is operating 20 "special trains" on its InterCity services. There will be no weekend DART or commuter services between Pearse station and Greystones, including bank holiday Monday, due to upgrade works.
Hundreds of passengers on flights between Ireland and southern England were delayed yesterday due to a computer failure in Britain early in the day which shut down the air traffic-control system there.
The breakdown of the 30-year-old system happened at 6 a.m., and although it was working again within an hour, the backlog of delayed flights continued during the day.
An Aer Rianta spokeswoman said that by afternoon there were still delays of up to three hours on flights between Ireland and the four main London airports.
