September Equinox Australia. In 2024, the first day of autumn in australia (southern hemisphere) will occur on tuesday, march 20 at sharp 02:07 pm australian eastern daylight time (aedt). That’s why in the earth’s southern areas, the september equinox is known as the spring equinox.

On the day of the autumn (september) equinox, the sun, moving along the ecliptic, crosses the celestial equator, moving from the northern hemisphere to the southern. That’s why in the earth’s southern areas, the september equinox is known as the spring equinox.