The status yellow high temperature warning has been extended to run until Saturday morning.
It was due to run out tomorrow with the mercury expected to get as high as 30 degrees nationally, and temperatures not to fall below 15 at night.
A similar orange alert for parts of Connacht, Leinster and along the border will run out tomorrow morning.
The news comes as a mother is appealing to parents to apply sunscreen correctly, after her son received second degree burns this week.
15 year old Bhrion had to receive hospital treatment for his burns, after spending the day at the beach.
His mother, Laura Daly says not allowing enough time for the sun cream to work was their biggest mistake.
“I think it was because he spent most of the time in the water.
“He was in the water for over 3 hours.
“Each time he came out, we reapplied the sun cream.
“I made the fatal mistake not making him sit and wait 5 or 10 minutes to let it dry in.
“We only waited a minute and I said ‘yeah grand, go on’.”