Sun seekers and swimmers are being urged to stay away from some beaches in the east and south after an influx of dangerous jellyfish.
Portuguese man o'war and lion's mane jellyfish have been spotted at popular coastal spots as temperatures rise. Both are considered among the most venomous jellyfish in Ireland.
Lifeguards at Sandycove in south Dublin are now flying a red warning flag and have erected signs warning the public about the presence of lion's mane jellyfish in the area. The creature can grow up to two metres in diameter.
Dún Laoghaire-Rathdown County Council has urged bathers not to enter the water.
"We have raised the red warning flag in Sandycove and erected signs warning swimmers of the presence of jellyfish in the water and washed up on the beach," the council said in a statement.
"Bathers are advised not to enter the water due to the presence of these jellyfish whose sting can be dangerous and cause serious symptoms including nausea, vomiting and respiratory distress."
Meanwhile, a deadly Portuguese man o'war jellyfish was found by lifeguards yesterday afternoon at Ballybunion beach in Co Kerry. While the beach has not been closed to swimmers, lifeguards say they are monitoring the situation carefully.
Stings from a lion's mane or Portuguese man o'war can inflict severe stings and cause anaphylactic shock in some cases. The allergic reaction provoked by the venomous sting can be fatal.
John Leech, of Irish Water Safety, said the two types of jellyfish were "not to be messed with". "Tell children to stay away from them, and don't let them poke the jellyfish," he added.
The warm conditions are set to continue over the weekend and into next week, according to Met Éireann. Forecaster Joan Blackburn said that while dry weather and consistent sunshine nationwide was not guaranteed, high temperatures would last into this weekend and early next week.