Met Éireann has issued a thunderstorm warning for Munster and Connacht, which is expected to last 24 hours.
The Status Yellow warning will be in place from 6pm on Friday until 6pm on Saturday, affecting 11 counties overall.
Met Éireann said: "Heavy showers or longer spells of rain with thundery downpours in some places may lead to spot flooding, with the highest rainfall totals likely to be near the west coast on high ground.”
A Status Yellow weather alert is for weather conditions that do not pose an immediate threat to the general population but only those exposed to risk by nature of their location or activity, according to Met Éireann.
Leinster is expected to remain mostly dry with isolated showers occurring in the evening.
Other than rain, temperatures will remain high showing 14 to 19 degrees in the northeast of the country but will be noticeably cooler in the southwest in the late afternoon.
It will be cooler in the southeast of Ireland as winds will become westerly, with strongest winds seen nearer to the coast.
Tonight, alongside the downpours, the wind will continue in the west, turning heavy and thundery throughout the night.
Moving further to the east it will be clearer, but isolated showers will still be present.
Temperatures will drop to between 7 and 10 degrees with a fresh southerly breeze through the night.
Saturday is due to be “an unseasonably cold, windy and wet day” with heavy rain continuing in the western half of the country.
Highest temperatures will be between 11 to 17 degrees, coolest in the west with a fresh to strong wind.
Sunday will show a mix of sunny spells and widespread heavy and possibly thundery showers. Temperatures will rise between 13 to 16 degrees with moderate to fresh southwesterly winds.