The spell of warm weather is expected to end today, dispelling hopes that 20 degree-plus temperatures in some parts of the country would continue over the bank holiday weekend.
Met Éireann said that while today would begin with sunshine, cloud would drift from the west bringing rain in the evening.
The east of the country would enjoy the best temperatures, between 15 to 23 degrees today, Met Éireann said.
There will be some sunshine tomorrow . . . but this will be accompanied by scattered showers and temperatures averaging about the mid-teens.
Monday will see a return of dry and bright conditions but temperatures will persist about the mid-teens.
Some of those who had decided not to take their chances on good weather at home but depart to sunnier climes instead said they were hampered by slow security queues at Dublin airport yesterday morning.
One caller to The Irish Times said it took more than 45 minutes to clear security while another said only 21 staff were manning security at the airport's main terminal, pier B. Three out of seven clearance points were unmanned, the second caller claimed.
But Dublin Airport Authority spokeswoman Siobhán Moore said it had recorded a maximum security timing of 13 minutes.
"This is something we're very careful about. We have opened two new security channels and recruited an additional 100 staff for those, 30 of whom have already come on.
"We also moved forward the opening of passenger security clearing by one hour yesterday to 4am to facilitate extra passengers. If someone is excited and agitated about going on holiday, a 13-minute wait could feel like 45 minutes."
Meanwhile, heavy holiday traffic was expected on the roads, particularly between the west and east coasts. Nicola Hudson of AA Roadwatch said heavy volumes were also expected to head southwards towards Cork and Kerry because of the large number of events and festivals in Co Cork.
"N8 Dublin-Cork southbound traffic will carry heavy volumes from Dublin as there is plenty happening in Co Cork. Delays are to be expected at Abbeyleix, Durrow and Urlingford," she said.
An Garda Síochána warned motorists to drive carefully. Three people died on the roads over the May bank holiday weekend last year.
A Garda spokesman said: "Enforcement of speed limits and drink driving legislation will be a priority for Garda enforcement this weekend."