What Is The First Day Of Fall 2025. In 2025, the autumnal (fall) equinox arrives on monday, september 22, marking the official first day of fall. How many days left until fall 2025?
The first day of autumn is in 2025 on september 22 (according to the astronomical definition). Summer begins with the summer solstice, friday, june 20, 2025, 10:42 p.m.