September is the ninth month of the year in the Julian and Gregorian calendars. Its length is 30 days. September in the Northern Hemisphere and March in the Southern Hemisphere are seasonally equivalent. In the Northern hemisphere, the beginning of the meteorological autumn is on 1 September. In the Southern hemisphere, the beginning of the meteorological spring is on 1 September. . September marks the beginning of the ecclesiastical year in the Eastern Orthodox Church.
https://en.wikipedia.org/wiki/September