Autumn in 2023 started on Saturday, September 23. This date marks the astronomical autumnal equinox in the Northern Hemisphere, which is when day and night are approximately equal in length. The autumn season then lasted until the winter solstice on December 21, 2023.

Meteorologically, autumn can also be said to start on September 1, which is used for consistent seasonal statistics, but the widely recognized astronomical start is September 23.