Fall Equinox Date 2025. The date of the autumnal equinox shifts slightly depending on the year, but it will almost always occur on sept. The first day of fall in 2025 arrives with the fall equinox on sunday, september 22, 2025, at 8:44 a.m.
Autumn equinox 2025 (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. 22, the fall equinox formally heralds in autumn and marks the end of summer in the northern hemisphere.