When Does Fall Start 2025 Usa. The official first day of fall, otherwise known as the autumnal equinox, is this weekend in the northern hemisphere. When do the four seasons start in 2025—for spring, summer, fall, and winter?

That’s the day of the autumnal equinox when day and night are nearly equal in length. The official first day of fall, otherwise known as the autumnal equinox, is this weekend in the northern hemisphere.