Diwali (or Deepavali, the "festival of lights") is an ancient Hindu festival celebrated in autumn (northern hemisphere) or spring (southern hemisphere) every year. Arguably the most important festival in Hinduism, it is an official holiday in Fiji, Guyana, India, Pakistan, Malaysia, Mauritius, Nepal, Singapore, Sri Lanka, Suriname and Trinidad and Tobago. The festival spiritually signifies the victory of light over darkness or good over evil, knowledge over ignorance, and hope over despair. Its celebration includes millions of lights shining on housetops, outside doors and windows, around temples and other buildings in the communities and countries where it is observed. The festival preparations and rituals typically extend over a five-day period, but the main festival night of Diwali coincides with the darkest, new moon night of the Hindu Lunisolar month Kartika. In the Gregorian calendar, Diwali night falls between mid-October and mid-November.
Source: wikipedia.org | wikidates.org
In 2017 Diwali in USA in USA falls on October 17.