Asan, Guam offers 1 beach perfect for sunbathing, surfing, swimming, and more. Asan, Guam, is known for the War in the Pacific National Historical Park. The best time to travel to Asan, Guam, is from January to May, with average air temperatures around 80°F (27°C) and water temperatures near 82°F (28°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!