The 2013 Ballyshannon Folk Festival occurs the August Bank Holiday weekend (the first weekend in August), from August 1st to August 4th. (The poster says the 2nd to the 4th but the Web site says the 1st to the 4th).
Schedule and details are available at the Festival Web site:
Ballyshannon, County Donegal, Ireland. Ballyshannon is approx 3.5 hours from Dublin and 3.5 hours from Shannon Airport. Belfast is 2.5 hours away.