Because of their height, Lahul and Spiti have a very cold climate during winter months. Summer is quite pleasant. This often results in disruptions to electricity and transport, and there is little tourism during the cold winter months. However, the Spiti valley is accessible all year along the Old Hindustan Tibet road from Shimla to Kaza. The Lahul valley is not accessible until June though. however from December to April helicopter services at weekly intervals are available.
The climate of Spiti is too cold to support even tundra vegetation, and much of the land is barren and wild. It is a rare phenomenon to see temperatures rising above 20°C during the summer months, even at the lower elevations.