September Equinox 2025 Uk. The autumn equinox marks the start of the season, meaning it’ll take place on september 22 this year. The two equinoxes happen on 20 march (spring equinox) and 22 september (autumn equinox) and the days and nights should roughly be the same length.
According to the meteorological calendar, the first autumn day is sunday 1st september 2025. The equinox in the northern.