when is the first day of fal

The first day of fall (autumn) in 2025 is Monday, September 22, at 2:19 p.m. This corresponds with the autumnal equinox, the astronomical event that marks the start of fall in the Northern Hemisphere. On this day, day and night are approximately equal in length. Fall will then last until the winter solstice, around December 21, 2025. There is a difference between the astronomical definition of fall, starting with the equinox, and the meteorological definition, which often marks fall as beginning on September 1st. However, the official and widely recognized start of fall for 2025 is September 22 according to the equinox.