The best time to visit Calais, Maine, is during the summer months, from June to August, or in the early fall, during September and early October.Summer offers the warmest weather, with average temperatures in the 70s Fahrenheit, making it ideal for outdoor activities like exploring the St. Croix International Historic Site, enjoying the waterfront, or taking boat tours on the St. Croix River. The longer daylight hours also allow for more sightseeing. This time of year is especially good for families, as kids can enjoy the various parks and outdoor spaces without the chill of other seasons.For couples or those seeking a more tranquil experience, early fall is an excellent option. The weather remains pleasant, with crisp air and fewer crowds, and the changing foliage provides beautiful scenic drives along Route 1.