What Day Is The First Day Of Fall 2025 Usa. This is the official start of fall, astronomically speaking. The first day of autumn often called fall (september equinox or autumnal equinox) is when the sun shines directly on the celestial equator passing from north to south and the length of day and night are almost the same.

Download the monthly calendar for the autumn of 2025. The first day of fall in 2024 arrives with the fall equinox on sunday, september 22, 2024, at 8:44 a.m.