The 2025 March equinox has arrived, marking the Sun’s transition to the Northern Hemisphere sky as the Southern Hemisphere embarks on six months of more darkness than daylight.

What is the equinox?

Earth experiences two equinoxes each year, one in late March and the other towards the end of September. On both occasions, the equinox marks the date on which the Sun appears to be positioned directly above Earth’s equator. Following the equinox, the sun appears to move over either the Northern or Southern Hemispheres from the perspective of someone standing at the equator.

Image: Orientation of the Sun relative to Earth on the dates of the equinoxes.

This year’s March equinox occurs at 09:02am UTC on March 20, which is 8:02pm in Sydney, 5:02am in New York, 9:02am in London and 2:32pm in Mumbai.

Following the moment of the March equinox, the Sun will appear to be positioned north of Earth’s equator (for someone standing at the equator). This makes nights become longer than days in the Southern Hemisphere based on the amount of time between sunrise and sunset each day, while days will become longer than nights in the Northern Hemisphere.

Change of seasons

While the equinox has no direct influence on day-to-day weather across the planet, it does mark a seasonal transition for both hemispheres. The March equinox marks the start of the astronomical autumn in the Southern Hemisphere and the astronomical spring in the Northern Hemisphere. This is about three weeks later than the beginning of the meteorological autumn and spring, which are more aligned to average temperature trends and begin at the start of the month each equinox occurs in.

Most countries around the world use equinox dates to mark the start of autumn and spring, including the United States and the United Kingdom. However, some countries declare the start of each season based on the meteorological season dates, including Australia and New Zealand.

So, while Australia farewelled summer and commenced autumn three weeks ago, those in the US are officially kicking off their spring today.