Naag Panchami falls in the middle of the monsoon. It is a Hindu festival that worships the serpent god, Naag. Pictures of Naag are posted in doorways, and milk is offered to him. It is believed that worshipping Naag protects against snake bites. This festival marks respect to serpents as the water guardians, and to ensure regular rainfall in the Kathmandu Valley.

Source: https://www.insidehimalayas.com/