The first day of fall in 2025 is Monday, September 22. This day is also known as the Autumnal Equinox, which marks the moment when the Sun crosses the celestial equator moving southward, resulting in nearly equal day and night lengths
. In the Northern Hemisphere, fall begins on this date and lasts until December 21, when winter starts
. The exact time of the equinox in 2025 is at 2:19 PM EDT (18:19 UTC)
. The Autumnal Equinox is the astronomical start of fall, differentiating it from meteorological definitions that may consider September 1 as the start of the season
