Today could be the hottest day of the year so far.
Met Éireann is forecasting temperatures of up to 28 degrees in Leinster and Ulster and 26 degrees in Waterford.
However, severe downpours, hail and spot flooding could follow.
A yellow thunderstorm warning will be in place throughout Ireland from 4pm today until 9am tomorrow.
Cathal Nolan, from Ireland's Weather Channel, says Leinster will bear the brunt of the storm.
"Initially from 4pm onwards, isolated thunderstorms could develop in pretty much any part of the country," he said.
However, it's through the evening time that we're likely to see more organised thunderstorms developing in the eastern half of the country and they will continue to push northwards through the eastern areas throughout the course of the evening and overnight bringing with it the risk of some frequent lightning and localised flooding in places.
Mr Nolan warned the thunderstorms forecasted could be quite strong.
"Certainly in terms of thunderstorms today could be quite severe, the environmental conditions are all in place for the development of some quite strong thunderstorms through the afternoon and the evening.
"It seems as though eastern parts will certainly see the brunt of those storms, breaking out from around 4pm onwards and probably peaking through the evening hours.
"With that, there could be some frequent lightning, hailstones and indeed, spot flooding could be an issue in one or two locations too."
