Wailua, United States offers 1 beach perfect for sunbathing, surfing, swimming, and more. Wailua is known for Wailua River State Park and the Fern Grotto. The best time to travel to Wailua, United States, is from April to June, with average air temperatures around 75-85°F and water temperatures near 75°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!