When Is The First Day Of Fall 20223. The first day of autumn often called fall (september equinox or autumnal equinox) is when the sun shines directly on the celestial equator passing from north to south and the length of. Edt in the northern hemisphere.
The equinox occurs at the same moment worldwide. The autumnal equinox—also called the september equinox or fall equinox—arrives on thursday, september 22.