Opcina Milna, Croatia offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Opcina Milna is known for its picturesque harbor and the historic Church of Our Lady of Annunciation. The best time to travel to Opcina Milna, 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!