Tribunj, Croatia offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Tribunj, Sibenik Knin, Croatia, is known for its annual Donkey Race and the historic St. Nicholas Fortress. The best time to travel to Tribunj, Croatia, is from June to September, when the average air temperature is around 75°F (24°C) and the sea temperature is approximately 77°F (25°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!