A temperature of 27.1 degrees celsius was recorded at Mount Dillon in Roscommon.
A mostly dry and sunny weekend is being forecast with highs of 27 degrees expected.
The RNLI's Lisa Hollingham is urging to people to mind themselves near water over the next few days:
"Always have a means of raising the alarm should anything happen. So if you can bring a phone in a waterproof page that's ideal. If you're going swimming, make sure you're wearing a bright coloured swim hat, go with the buddy, never go on your own so that somebody else can raise the alarm if anybody gets into difficulty. To raise the alarm ring 112 or 999, and ask for the Coast Guard."
