First Day Of Autumn 2025 Usa. Autumn 2025 starts on monday, september 22nd in the northern hemisphere, with daylight time shortening and the leaves begining to fall with the changing tilt of the earth's axis. The autumnal equinox, or the first day of fall in the northern hemisphere takes place every year on september 22nd or september 23rd.

In the southern hemisphere, the start of fall will be on march 20, 2025, at 09:02 gmt (05:02 a.m. First day of autumn falls on september 22 this year.