Longboat Key, United States offers 7 beaches perfect for sunbathing, surfing, swimming, and more. Longboat Key is known for its pristine beaches and luxury resorts. The best time to travel to Longboat Key, United States, is from March to May, with average air temperatures ranging from 70 to 85 degrees Fahrenheit and water temperatures around 75 degrees Fahrenheit. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!