A status yellow thunderstorm warning is now in place across the country until 9am on Friday morning.
Severe downpours, hail showers and spot flooding are expected.
It is as a result of the high temperatures felt across the country today.
Met Éireann's Jean Byrne says predicting which areas will experience the stormy weather is tricky.
“It is difficult to know because they could turn up practically anywhere, really," she said.
“It looks as if they will be most likely be coming up from the south, later this afternoon into this evening.
“But they could really develop anywhere in that heat.
“Tonight they are most likely across Connacht and Ulster.”
Met Éireann has warned that: “Heavy thunderstorms are expected to develop later on Thursday and Thursday night with some severe downpours, hail and spot flooding.
“Due to the localised nature of thunderstorms some parts of the country will remain dry.”
Today has been tipped to be the hottest day of the year with Met Éireann forecasting temperatures of up to 28 degrees in Leinster and Ulster.
The forecaster is predicting more showers across the weekend, but with temperatures remaining in the high teens.
They said there will be isolated heavy showers on Friday morning, but by early afternoon “persistent rain will spread across much of Munster whilst showers develop in many other regions.
“Staying warm and humid in northern and eastern counties with highest temperatures of 20 to 24 degrees but turning much fresher further south and west with maximum temperatures of 16 to 19 degrees.”
Saturday will see “frequent showers” with Met Éireann saying some will turn heavy “especially in parts of the north and northeast of the country.” They expect “top temperatures between 14 and 17 degrees.”
Met Éireann added: “Sunday will see further showers although less frequent than Saturday with the best of the dry and bright weather in the south and east of the country.
“Top temperatures 15 to 18 degrees with a moderate to fresh and gusty southwest to west winds strong along west and northwest coasts.”