Autumn Equinox 2025 Australia Time. Autumn equinox 2025 (beginning of astronomical autumn) on the day of the autumn (september) equinox, the sun, moving along the ecliptic, crosses the celestial equator, moving from the. The days are becoming shorter, and at the equinox, the length of day will be 12hrs.

Sydney the exact moment of the autumnal equinox in 2025 is 21 june, at 12:42:02. Learn more about australian autumn equinox 2025 here.