Tihar celebrates for five days starting from August 15th in the Nepalese calendar(late October or early November in the Gregorian calendar) every year, that is the 15th full moon day in the eighth month of the Hindu calendar.
In Nepal, Tihar is held in high regard, only second to the Dashain. It's is also known as the most beautiful festival. In some parts of India, it even replaced Dashain as the largest festival. Tihar falls on November 13th and lasts until the 17th in 2020.
https://www.greattibettour.com..../nepal-tours/tihar-f