Uttarakhand is a year round destination, many of the regions popular attractions are located in the cool area of the terai and you can even visit it during summers because it never gets too hot even then. Uttarakhand has pleasant temperature during summers which makes it best time to visit the region. However monsoons are a little hard in Uttarakhand, in the hilly regions there are landslide hence it’s advisable to avoid going there in monsoons. Post monsoons the weather is beautiful so you can visit between September to November.