The start of fall in 2025, also known as the autumnal equinox, is on Monday, September 22, 2025. This marks the astronomical beginning of the fall season in the Northern Hemisphere. The fall season then continues until the winter solstice on December 21, 2025. Meteorological fall, based on calendar months, begins earlier on September 1 and lasts through November 30.

Key Points:

• Astronomical Fall Start: September 22, 2025 (autumnal equinox)

• Meteorological Fall Start: September 1 to November 30

• The autumnal equinox is when day and night are approximately equal in length.
• From the equinox onwards, daylight hours progressively shorten as the season moves toward winter.

Thus, the official and most widely recognized start of fall in 2025 is September 22.