Day Fall Equinox 2024. The autumnal equinox arrived sunday, marking the end of astronomical summer and the first day of fall in the northern hemisphere. On that day, the autumnal equinox will occur, marking the beginning of fall.

Here’s everything you should know about the fall equinox—plus our favorite fall facts, folklore, photos, and. Autumnal equinox, two moments in the year when the sun is exactly above the equator and day and night are of equal length;