Autumn Equinox 2024 Southern Hemisphere Calendar. Speaking of balance, the sun’s transition into libra also very fittingly marks the autumn equinox, aka the first official day of fall here in the northern hemisphere — and. The september equinox marks the beginning of fall in the northern hemisphere and the first day of spring in the southern hemisphere.

Autumnal/fall equinox north of the. 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.