Met Éireann has issued a status yellow weather warning for Friday, with a risk of localised flooding in western and southern counties.
The national forecaster said rainfall totals of 30-50mm were expected during 6am on Friday and 6am on Saturday in Cos Donegal, Clare, Cork, Kerry and Limerick.
Those attending Electric Picnic in Co Laois face the possibility of thunder storms on Friday, followed by constant showers, strong winds and, occasional spells of sunshine.
According to Met Éireann the local forecast for Stradbally, the Electric Picnic venue, is for possible thunder and periods of rain throughout Friday, with heavier spells as the day goes on and into the night.
The rain is set to become persistent on Saturday with 9mm of rainfall forecast between 1am and 7am.
By Saturday night this rain will ease to showers.
Sunday will see an improvement and it is set to be the best day weatherwise for festival goers.
In Dublin’s Croke Park on Sunday forecasted showers will be broken-up with periods of “bright and cool” conditions - at least off the pitch.
Thursday
Met Éireann’s detailed forecast for Thursday is for showers, frequent in the west and north but more isolated elsewhere.
It will be mostly cloudy but there will be occasional sunny intervals. Top temperatures of 17 to 20 degrees in fresh to strong and gusty southwest winds.
Outbreaks of rain will develop in west Munster, Connacht and Ulster on Thursday night, turning heavy and persistent towards dawn on Friday.
Elsewhere, a good deal of dry weather but with the odd shower. Minimum temperatures of 12 to 15 degrees in fresh to strong and gusty southwest winds.
Friday
Friday will see outbreaks of rain will extend to most of the country on Friday. with a risk of thunder in the midlands. The rain will be heavy and persistent in west Munster, Connacht and much of Ulster with the risk of localised flooding.
The rain will be patchier elsewhere with decent dry periods, especially in the southeast. Maximum temperatures ranging 16 to 20 degrees in fresh and gusty south or southwest winds.
Saturday
On Saturday morning, the forecast is for heavy rain overnight giving way to bright or sunny spells and showers. Highest temperatures 15 to 18 degrees in moderate west to northwest winds. The showers will become confined to Atlantic coasts overnight on Saturday. Lowest temperatures of 8 to 10 degrees in moderate westerly breezes but strong at times on Atlantic coasts.
Sunday
Sunday will probably provide the best of the weekend weather. It will be a fresh and cool day with sunny spells and scattered showers. Some of the showers will be heavy, especially in the northwest. Highest temperatures of 14 to 17 degrees with moderate to fresh west to northwest winds.
Initial forecasts suggest early next week is set to be largely dry and bright with some rain possible on Tuesday.
Temperatures are expected to be around normal.
