The most popular time to visit Glen Affric National Nature Reserve is in the summer, with long daylight hours and fairly warm weather. However, it is peak season in the Highlands, so it's a good idea to at least avoid school holidays and weekends. Autumn is a good alternative as the biggest crowds will have gone, and the valley is ablaze with rich, golden colours. Spring is another good option for seeing the vibrant yellow gorse bloom over the landscape.