Autumn Equinox 2024 Uk. Autumn equinox 2024 (beginning of astronomical autumn) on the day of the autumn (september) equinox, the sun, moving along the ecliptic, crosses the celestial equator,. This year autumn begins on 23 september 2023 and ends on 22 december 2023.

They also do this for the winter and summer. Based on the astronomical method of determining the seasons, autumnal equinox marks the beginning of fall.