Grand Lake, United States offers 2 beaches perfect for sunbathing, surfing, swimming, and more. Grand Lake is known for Rocky Mountain National Park, Grand Lake itself, and the historic Grand Lake Lodge. The best time to travel to Grand Lake, United States, is during the summer months of June to August, when the average air temperature is around 70°F (21°C) and the water temperature is approximately 65°F (18°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!