When Is The Autumnal Equinox 2024 Date. When is the autumnal equinox in 2024? Autumn equinox 2024 (beginning of astronomical autumn) on the day of the autumn (september) equinox, the sun, moving along the ecliptic, crosses the celestial equator,.

The autumn equinox usually occurs on the 22nd or 23rd september, but it has been known to occur on the days on either side of those dates. In 2024, the autumnal (fall) equinox arrives on sunday, september 22, marking the official first day of fall.