Greenlawn, United States offers 2 beaches perfect for sunbathing, surfing, swimming, and more. Greenlawn, Missouri, United States, is known for its proximity to the Mark Twain National Forest and the Ozark National Scenic Riverways. The best time to travel to Greenlawn, United States, is during late spring to early fall (May to September) when the average air temperature ranges from 60°F to 80°F, and water temperatures in nearby Long Island Sound range from 60°F to 75°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!