Naalehu, United States offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Naalehu, Hawaii, United States, is known for being the southernmost town in the United States and its proximity to the famous Punalu'u Black Sand Beach. The best time to travel to Naalehu, United States, is from November to April, with average air temperatures around 70-80°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!