Tipperary, Offaly, Kilkenny and parts of Galway may see temperatures exceed 30C today as the country prepares for a very hot day.
Counties Laois, Carlow and Westmeath will also see highs of 30C as inland areas will experience the warmest conditions.
Temperatures in Wexford, Mayo and Belfast are expected to reach 28C while Cork and Clare will see highs of 27C.
Met Éireann’s Status Yellow high temperature warning for Leinster and Munster will be extended to cover the entire country from 12pm today.
The country’s hot spell weather advisory also remains in place until midnight on Monday.
Meterologist Paul Downes said it will be slightly warmer today and temperatures are set to increase again tomorrow.
The country experienced its hottest August day in more than 19 years yesterday as a temperature of 30.5C was reached in Carlow.
Met Éireann said the maximum temperature of 30.5C was reached at Oak Park weather station on Thursday, which also recorded Wednesday’s highest value of over 29C.
Mr Downes said this record August high may be breached today and tomorrow.
The hottest ever August day, 31.5C recorded at Oak Park on August 2, 1995.
Mr Downes said there is a “growing chance” that this could be surpassed over the coming days and Met Éireann will be monitoring the situation.
He said there is a slight chance that the Status Yellow high temperature warning may be extended on Sunday for Leinster and Munster, but this is yet to be confirmed.
The decision will be based on whether or not the country experiences thundery showers on Sunday.
The high temperatures over the coming days may result in heat stress, especially for the more vulnerable of the population.
There is also a high solar UV index along with a risk of water related incidents.