Autumnal Equinox 2024 Dates Usa. 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, moving from the northern hemisphere to the southern. In 2024, it will be on september 22 at 08:44 a.m.

In 2024, it will be on sunday, sept. Find out when autumn (fall) starts and ends in 2024 according to astronomical and meteorological definitions.