Mount Vernon, United States offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Mount Vernon is known for the Skagit Valley Tulip Festival. The best time to visit Mount Vernon, United States, is in late spring (May to June) when the average air temperature is around 70°F (21°C) and water temperature in nearby bodies is approximately 65°F (18°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!