The best time to visit Castleton, Ontario, Canada, is during the summer months, from June to August, and the early autumn, specifically September.Summer in Castleton offers warm, pleasant weather, ideal for exploring the natural beauty of the Northumberland Hills and enjoying outdoor activities. The average daily temperatures range from the low 20s to mid-20s Celsius (70s Fahrenheit), making it comfortable for hiking, cycling, and visiting local farms. Many local events and farmers' markets are in full swing during this period, providing opportunities to experience the community's offerings.Early autumn, particularly September, is also an excellent time to visit. The weather remains mild, and the region transforms with stunning fall foliage, making it a picturesque destination for scenic drives and photography.