The first day of fall, also known as the autumnal equinox, typically occurs on September 22 or 23 in the Northern Hemisphere. In 2025, the autumnal equinox- and thus the official start of fall-will be on Monday, September 22, at 2:19 pm EDT
. The autumnal equinox is the moment when the Sun crosses the celestial equator going southward, resulting in nearly equal hours of daylight and darkness. This marks the transition from summer to fall, with cooler temperatures and shorter days following
. While meteorologists often consider September 1 as the start of fall for record-keeping purposes, the astronomical start of fall is defined by this equinox event
. In summary:
- Astronomical first day of fall 2025: Monday, September 22 at 2:19 pm EDT
- Common range: Usually September 22 or 23 (can vary between September 21 and 24)
- Significance: Sun crosses celestial equator; day and night are approximately equal in length
