Shadehill, United States offers 1 beach perfect for sunbathing, surfing, swimming, and more. Shadehill, South Dakota, United States, is known for Shadehill Reservoir and the adjacent Llewellyn Johns Recreation Area. The best time to travel to Shadehill, United States, is in late spring or early fall when the average air temperature is around 60-70°F and the water temperature is approximately 60°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!