Mountain Lakes, United States offers 3 beaches perfect for sunbathing, surfing, swimming, and more. Mountain Lakes, New Jersey, United States, is known for its picturesque lakes and the historic Mountain Lakes Club. The best time to travel to Mountain Lakes, 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!