Letterkenny, Ireland offers 4 beaches perfect for sunbathing, surfing, swimming, and more. Letterkenny is known for its proximity to Glenveagh National Park and the Wild Atlantic Way. The best time to travel to Letterkenny, Ireland, is from May to September, with average air temperatures around 50-65°F (10-18°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!