Autumnal Equinox Day 2024. In 2024 the autumnal equinox will occur on 22 september at 12.44pm gmt (1.44pm bst). This sunday, the autumnal equinox is upon us, and with it, a shift to shorter days, longer nights and the astronomical start of fall in the northern hemisphere.

The 2024 autumnal equinox arrived sunday at 8:43 a.m. Autumnal equinox, two moments in the year when the sun is exactly above the equator and day and night are of equal length;