Today is set to be the hottest day of the year but Met Éireann has issued a yellow thunder and lightning warning for all 32 counties.
Temperatures will soar to 28C "and maybe hotter" according to the national meteorological service, but as the day advances thunderstorms will roll in, bringing with them localised flooding and lightning.
A status yellow thunderstorm alert will be in place until tomorrow morning.
"It will be hectic weather. It's going to be interesting over the next 24 or 36 hours," meteorologist Paul Downes said.
"It's going to get warm today, with temperatures up to 28C or even higher than that. That would be the hottest day of the year."
Mr Downes said that, after a "muggy" night last night, the mist of this morning will dissipate and it will turn into a nice day. As evening approaches, however, incoming clouds will bring a thunderstorm likely to cause spot flooding and lightning.
"Today will be very humid. Misty patches will clear to give sunny spells. Temperatures will be between 22C and 28C, warmest in the East," he said.
"There is a yellow thunderstorm warning out so expect widespread showers later in the evening and overnight.
"Those thundery deluges could bring some hail and localised flooding as well.
"Thunderstorms are expected to continue overnight with a few persisting through the morning but fresher conditions coming in later on tomorrow night and through the weekend as well.
"The risk of localised flooding is there. There could be some very heavy deluges. Certainly there could be some lightning with some of these storms as well.
"There is definitely a danger to lightning. You should stay indoors and stay away from trees and the likes of that."
Thunderstorms will continue into tomorrow in eastern counties, Mr Downes said, with cooler temperatures over the weekend.
The extended outlook into the early days of next week is for continued unsettled conditions with rain or showers at times.