What Day Is The Autumnal Equinox 2024. The autumnal equinox, also known as the september equinox in the northern hemisphere, begins on the day when the sun appears to cross the celestial equator and heads. Find out the dates, history and traditions of autumnal equinox.
The autumnal equinox in september ushers in a change of season. March 19, 2024 (vernal equinox) summer: