The best time to visit Mount Desert is during the late spring to early autumn months, specifically from May to October, when the weather is most agreeable for outdoor activities.May and early June offer a peaceful experience with fewer crowds and blooming wildflowers, making it ideal for those who prefer a tranquil visit and enjoy hiking or nature photography. The temperatures are mild, great for exploring Acadia National Park without the summer heat.For those who enjoy warmer weather and a full range of activities, July and August are prime months. All attractions, restaurants, and shops are fully open, and the island is buzzing with visitors. While it's the busiest time, it's great for families looking to take advantage of boat tours, swimming, and various outdoor programmes.September and October bring stunning autumn foliage and cooler, crisp air. The crowds begin to thin, but most establishments remain open.