Porto Istana, Italy offers 3 beaches perfect for sunbathing, surfing, swimming, and more. Porto Istana, Sardinia, Italy, is known for its stunning beaches and crystal-clear waters, particularly the Spiaggia di Porto Istana. The best time to travel to Porto Istana, Italy, 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!