It'll be in place until Saturday.
A status yellow high temperature warning takes effect from tomorrow until Saturday morning.
Met Éireann is warning of daytime highs of 27 degrees and overnight lows of 15 degrees - which will lead to difficult sleeping conditions.
It's also advising the public of the risk from heat stress in the coming days.
Alan O'Reilly of Carlow Weather says we could see the hottest day of the year before the weekend: