Coolin, United States offers 4 beaches perfect for sunbathing, surfing, swimming, and more. Coolin, Idaho, United States, is known for Priest Lake, a popular destination for outdoor recreation and natural beauty. The best time to travel to Coolin, United States, is in July when the average air temperature is around 80°F (27°C) and the water temperature in nearby Priest Lake is approximately 70°F (21°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!