The worst weather of Electric Picnic weekend will be experienced by those camping at the Co Laois site tomorrow night, according to Met Éireann.
Weather at the three-day music and arts festival at Stradbally, which gets underway tomorrow, will be "unsettled", according to meteorologist Joan Blackburn.
The weather would be "largely dry with reasonable temperatures of 17 to 18 degrees, with a bit of drizzle", but a heavy band of rain was expected tomorrow night which would last until about noon on Saturday, she said.
"If it hasn't cleared by then it will have by early afternoon. It will be drier for the rest of Saturday though the temperatures won't be any great shakes - about 15 or 16 degrees. It will be showery again Sunday afternoon.
"So there will be two spells of rain for the Picnic - Friday night, all night. And Sunday afternoon."
Gates are due to open to the site at 9am tomorrow with The Little Smoke - the first of the weekend's acts - taking to the stage in the Cosby tent at 3pm.
Over the weekend there will be 200 performers playing on 17 stages. There will be 4,000 staff involved in setting up the festival and 80 food stalls on site.
Some 100,000 cups of coffee will be sold and 180,000 pints of beer pulled. Just 650 bottles of champagne will be consumed and a total of 800 portable toilets are waiting to serve on site.
Gardaí are advising where possible that people use public transport, or car-pool. The Minister of State for Public Transport Alan Kelly echoed the call urging anyone attending the "Electric Music (sic) festival" to "leave the car at home if you can".
Those in cars should follow Garda signs and the instructions of point gardaí on duty.
According to the AA delays can be expected on the N80 Portlaoise to Carlow road, on the M8 Cork to Dublin road at Junction four Urlingford and on the M7 Dublin to Limerick road southbound at Junction 16 Portlaoise east, and, northbound at Junction 17 Portlaoise centre.
All car parks around the site will be clearly marked and free-of-charge. They will be accessed via the Abbeyleix/Cork road. Campervans, which could access the site from today, should do so via the Timahoe road only. Disabled access, and family camping and parking access, are also via Timohoe Road.
Bus Éireann is operating bus services to the Picnic, from Dublin, Galway and Cork. Dublin buses will operate from 9am tomorrow to the site, until 6pm, leaving from Custom House Quay. They will run from 10am on Saturday and from 11am on Sunday. The fare is €28 return.
From Galway, buses leave at noon tomorrow from Eyre Square and the fare is €35 return. From Cork buses leave Parnell Place at 8 am tomorrow, with a return fare of €45.
For buses from Limerick contact www.kellytravle.ie. From Sligo, Longford and Leitrim contact www.fureysofsligo.com.
The nearest train station is at Portlaoise, a 15 minute drive from the festival. Shuttle buses will run from the station to the festival, at €5 each way.
Bike racks for cyclists will be available at gate number one.
