The Status Yellow warning is in place for; Clare, Cork, Mayo, Kilkenny, Limerick, Laois, Offaly, Galway, Kerry, and Tipperary.
Met Éireann have issued advice for the impacts of these high temperatures such as water safety, sleeping in the heat, forest fire threat, and animal welfare.
A weather advisory is currently in place all of the country warning of a very high UV index. Risk of heat stress, sunburns and other damages has increased.
An Garda Síochána has asked that motorists slow down in the heat and allow extra time for journeys as the roads are likely to be busier as people flock to outdoor events, beaches, lakes and parks.
The heatwave is to continue until Thursday at the earliest.
