Autumn Equinox 2025 Dates Usa. America the exact moment of the autumnal equinox in 2025 is 22 september, at 20:19:18. When do the four seasons start in 2025—for spring, summer, fall, and winter?
The first day of autumn is in 2025 on september 22 (according to the astronomical definition). The equinoxes (vernal & autumnal)