Grad Senj, Croatia offers 4 beaches perfect for sunbathing, surfing, swimming, and more. Grad Senj is known for the Nehaj Fortress and the Senj International Summer Carnival. The best time to travel to Grad Senj, Croatia, is from June to September, with average air temperatures around 75°F (24°C) and water temperatures around 72°F (22°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!