Autumn Equinox 2024. When is the autumn equinox? Because the fall equinox is not a fixed day but is rather based on an.

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,. According to the meteorological calendar, the first autumn day is sunday 1st september 2024.