Mehregan In the Zoroastrian religious calendar, Mehregan is celebrated on the sixteenth day of the seventh month. According to Fasli reckoning, this occurs on October 1. Modi (1922), pg 463, states that Mehregan should properly fall on the fall equinox (which is the first day of the seventh month), but it is usually performed on the name day of Mithra (16th day). http://www.cais-soas.com/CAIS/Celebrations/mehregan.htm