An Fhearthainn, Ireland offers 1 beach perfect for sunbathing, surfing, swimming, and more. An Fhearthainn, County Donegal, Ireland, is known for the stunning Glenveagh National Park and the historic Glenveagh Castle. The best time to travel to An Fhearthainn, Ireland, is from May to September, with average air temperatures around 55-65°F (13-18°C) and water temperatures around 55-60°F (13-16°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!