Autumnal equinox or variations, may refer to:

• September equinox, the autumnal equinox in the Northern Hemisphere
• March equinox, the autumnal equinox in the Southern Hemisphere

Other uses

• Autumnal Equinox Day (Japanese: 秋分の日, Shūbun no Hi), a public holiday in September in Japan
• Autumn Equinox: Amethyst Deceivers, a 1998 record by Coil
• "An Autumnal Equinox", a song from The Caretaker's 2016 album Everywhere at the End of Time - Stage 1