Monhegan Island Plantation, United States offers 1 beach perfect for sunbathing, surfing, swimming, and more. Monhegan Island Plantation is known for its Monhegan Island Lighthouse and the Monhegan Museum of Art & History. The best time to visit Monhegan Island Plantation is during the summer months of June to August, 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!