Autumn in 2023 began on Saturday, September 23. This date marks the astronomical autumn equinox, when day and night are approximately equal in length. The precise time of the autumnal equinox in 2023 was at 6:50 am GMT. Meteorologically, autumn starts earlier, on September 1, and runs through November 30. But the widely recognized start of astronomical autumn, based on Earth's tilt and orbit, was September 23, 2023.