Nine counties are listed as being most at risk.
Met Éireann has issued a Status Yellow thunderstorm and rain warning for Ireland.
Valid from shortly after 1pm on Friday until 8pm, the forecaster says there will be thunderstorms in places this afternoon and evening, along with lightning, hail and heavy downpours.
This will result in localised flooding and hazardous driving conditions, Met Éireann also said.
The counties most at risk of thunderstorms and rain are Clare, Galway, Kildare, Laois, Mayo, Offaly, Roscommon, Tipperary and Wicklow.
⚠️ Status Yellow - Thunderstorm & rain warning for Ireland ⚠️
Thunderstorms in places this afternoon & evening with lightning, hail & heavy downpours resulting in localised flooding & hazardous driving conditions. ⛈️ ☔️
— Met Éireann (@MetEireann) July 23, 2021
The weather update comes following a Status Yellow high-temperature warning being issued for Ireland earlier in the week. That remains in place until 9am on Saturday.
In terms of weekend weather, Saturday will be a mainly dry day with sunshine for most, though it will be hazier in the east.
Isolated showers will also develop in Munster and Connacht later in the day. Temperatures will range from 23 to 27 degrees generally but will be slightly fresher along the east coast.
Sunday will see sunny spells, along with some scattered showers developing in the afternoon.
It will be staying warm with temperatures between 22 and 26 degrees, yet it will feel a little colder than previous days on account of light to moderate breezes.
Next week's weather, meanwhile, will be rather changeable up to midweek with a mix of showers and dry spells as temperatures return back to more average values for mid-summer.