Winnetka, United States offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Winnetka, Illinois, United States, is known for the "Home Alone" house, which attracts fans of the iconic movie. The best time to travel to Winnetka, United States, is during the summer months of June to August, when the average air temperature is around 75°F (24°C) and the water temperature in Lake Michigan is approximately 68°F (20°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!