I visited Mussoorie in July, everyone knows that this is a rainy season for the hill station and lots of people avoid to go in this season. But believe me if you want to see the nature at its best, visit mussoorie in monsoon. Beauty of mussoorie is at its best during monsoon. Even though you can visit Mussoorie in winters and summers but I will recommend visiting at this time of the year. This is totally up to you. If you like to see the snow you should choose winter and if want to get a relief from heat in summer then this place is for you. Also, you will be getting less crowd and so you can enjoy in peace.