Autumn Equinox 2024 Uk Calendar. In 2024, the autumnal (fall) equinox arrives on sunday, september 22, marking the official first day of fall. In 2024, autumn will start on september 22 and end on december 21, which is when winter starts.
However, the astronomical calendar is based on the position of the sun in relation to the earth and changes each year โ known. The seasons are defined as spring (march, april, may), summer (june, july, august), autumn.