Fall 2023 in the USA, based on the astronomical definition, began on Saturday, September 23, 2023, at 2:50 a.m. ET. This date corresponds to the autumnal equinox, which marks the start of fall in the Northern Hemisphere. The fall season extends until December 21 or 22, 2023, depending on the calendar used. Meteorologically, fall is often considered to start earlier, on September 1, and run through November 30, but the official astronomical start for 2023 was the equinox date in late September.