The hot conditions will continue today with temperatures again expected to top 30 degrees in parts, with cooler conditions forecast over the weekend.
Yesterday was the warmest day of the year so far, with a high of 30.8 degrees recorded at Mount Dillon in Co Roscommon.
Met Eireann has two high temperature warnings in place until tomorrow morning.
Cathal Nolan, from Ireland's Weather Channel, says the hot conditions are to stick around for a little while yet.
"Today is probably the second last day of the heat wave.
"It looks as though we will see temperatures today pushing towards 30, maybe 31 degrees in some parts in the country.
"It's likely that Friday will probably be the last day of the heatwave, and with that temperatures on Friday are expected to get up to 28/29 degrees, before we see a bit of a tapering back as we head into the weekend, and the early days of next week."
