What Day Is The Fall Equinox 2024. Cdt) on september 22, 2024. Autumnal equinox — is an astronomical phenomenon, when the sun in its visible motion along the ecliptic crosses the celestial equator.

In 2024, the autumnal equinox will take. The first day of fall is sunday, september 22, 2024—the same day as the autumn equinox—in the northern hemisphere.