Grand Coulee, United States offers 1 beach perfect for sunbathing, surfing, swimming, and more. Grand Coulee is known for the Grand Coulee Dam, a massive hydroelectric dam on the Columbia River. The best time to travel to Grand Coulee, United States, is in late spring or early fall when the average air temperature is around 60-70°F, and the water temperature in nearby bodies is approximately 50-60°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!