Charlestown, United States offers 23 beaches perfect for sunbathing, surfing, swimming, and more. Charlestown, Maryland, United States, is known for the historic Charlestown Historic District and the nearby Elk Neck State Park. The best time to travel to Charlestown, United States, is in late spring (May to June) when the average air temperature is around 65-75°F and the water temperature is approximately 55-65°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!