What Is The First Day Of Fall 2025. The 2025 autumnal equinox happens at 8:43 a.m. In 2025, the autumnal (fall) equinox arrives on sunday, september 22, marking the official first day of fall.

The 2025 autumnal equinox happens at 8:43 a.m. Meteorological fall kicks off on september 1, but the official start of autumn doesn’t hit until thursday, september 22nd at 8:43 a.m.