Autumn Equinox 2025 Dates Usa. Spring equinox 19 march, summer solstice 20 june, autumn equinox 22 september, winter solstice 21 december. When do the four seasons start in 2025—for spring, summer, fall, and winter?

This is because meteorological autumn always starts on 1 september but the astronomical one begins at equinox (22 september this year). In 2025, the autumnal (fall) equinox arrives on sunday, september 22, marking the official first day of fall.