Mackinac Island in August

May through October is your window – most businesses close for winter, and ferry service gets spotty. July and August bring the biggest crowds and highest prices, but also the warmest weather and longest daylight hours. June hits the sweet spot with mild weather, blooming lilacs, and smaller crowds than peak summer. The Lilac Festival in early June celebrates the island's 300+ lilac varieties with parades and tours. September offers gorgeous fall colors and cooler temperatures perfect for biking. October can be magical with autumn leaves, but some restaurants and shops start closing for the season. May feels a bit chilly for swimming, but you'll have the island mostly to yourself and pay lower hotel rates. Avoid major summer weekends if you hate crowds. The island can feel claustrophobic when multiple ferries dump thousands of day-trippers onto Main Street. Winter visits are possible but limited – only about 500 people live on the island year-round, and most tourist infrastructure shuts down.