The hot conditions will continue today during the Orange weather warning 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.
Longford and eastern parts of Mayo baked under 30.5 celcius at a peak as a result of the first-ever Status Orange heat advisory.
Met Eireann has two high temperature warnings in place until tomorrow morning.
Temperatures remained above 20 degrees in parts of the country overnight.
Cathal Nolan, from Ireland's Weather Channel, says the hot conditions are to stick around for a little while yet.