The Southern Hemisphere’s spring equinox will occur early next week, meaning days are about to become longer than nights across Australia.

What is the spring equinox?

The spring equinox (also known as the vernal equinox) refers to the date when the Sun appears to be positioned directly above Earth’s equator. This happens twice each year - once in March and again in September.

Day and night are roughly equal in length for most places on Earth around the dates of the equinoxes. In September, the Southern Hemisphere starts to become more tilted towards the Sun and the Northern Hemisphere tilts away from the Sun. This causes days to be longer than nights in the Southern Hemisphere for the following six months.

Image: Orientation of the Sun and Earth on the date of the spring equinox.

When is the spring equinox in Australia?

The spring equinox will occur early morning at 4:19am AEST on Tuesday, September 23, 2025. On this date, there will be roughly (but not exactly) 12 hours between sunrise and sunset across Australia.

You can check the sunrise and sunset times for your area on the Weatherzone app.

Image: Daily Forecast for Condobolin, NSW, on the Weatherzone app.

While Australia’s meteorological spring started on September 1, the astronomical spring for the Southern Hemisphere begins on the date of the equinox. The reason for this difference is due to the meteorological season more closely matching the annual temperature cycles experienced most populated areas on Earth.

Image: The difference between Earth’s astronomical and meteorological seasons. Source: NOAA Office of Education/Kaleigh Ballantine

Meanwhile, for the Northern Hemisphere, the autumn/fall equinox will occur at 6:19pm UTC on Monday, September 22, 2025. Following the moment of the equinox, the Northern Hemisphere will embark on six months of more darkness than daylight.