Autumnal Equinox 2025 Date. 22 or 23 depending on the year. According to the astronomical autumn, the autumn equinox will signal the start of the season and begin on the 22nd of september.

In different time zones, the date of the equinox may differ by a day, so it is important to indicate your exact location. The fall — or autumnal — equinox can land on sept.