Grad Omis, Croatia offers 18 beaches perfect for sunbathing, surfing, swimming, and more. Grad Omis is known for the Cetina River, the Omis Riviera, and the historic Mirabella Fortress. The best time to travel to Grad Omis, Croatia, is from June to September, with average air temperatures around 75-85°F (24-29°C) and water temperatures around 72-77°F (22-25°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!