Met Éireann has issued a nationwide status yellow high temperature warning.
The forecaster says the warm and humid weather with daytime temperatures in excess of 27 degrees in many areas away from coasts.
Night-time temperatures are set to not fall below 15 degrees.
This will potentially lead to heat stress, uncomfortable sleeping conditions and a risk of water-related incidents.
The warning is valid from 8am on Thursday morning until 8am on Saturday morning.
