The best time to visit Millville is during the summer months, from June to August, and the early autumn, specifically September and early October.Summer offers the warmest weather, making it ideal for enjoying the outdoors and the St. John River. The days are long, and temperatures are generally pleasant for activities like hiking, fishing, or exploring the local area. Many local events and markets are also in full swing during this period.Early autumn provides a different but equally appealing experience. The weather remains comfortable, and the region's foliage transforms into stunning shades of red, orange, and gold, particularly along the river valleys.