Bar Harbor in March

June through October offers the best weather, but each month brings trade-offs. July and August mean warm days perfect for hiking and swimming, but also crowds, higher prices, and traffic jams on Route 3. September is the sweet spot — comfortable temperatures, fewer crowds, and early fall colors starting to show. October brings spectacular foliage but chilly mornings and some businesses closing for the season. June offers wildflowers and reasonable crowds, though ocean water stays frigid. Many restaurants and attractions close from November through April, and while winter has its own stark beauty, Bar Harbor essentially hibernates. The Island Explorer buses only run late June through Columbus Day, which limits your car-free options outside that window.