When Is First Day Of Fall 2024 Uk. An equinox is one of two days in the year when the sun crosses the equator and day and night become equal in length. But again, this is only for the northern hemisphere, since the southern hemisphere experiences the reverse, and.

The first day of fall is sunday, september 22, 2024—the same day as the autumn equinox—in the northern hemisphere. In 2024, this happens on september 22, at 12:44.