In 2025, the March equinox falls on March 20th at 3:01 PM AEDT, a Thursday. This signifies the astronomical start of autumn in the Southern Hemisphere and the beginning of spring in the Northern Hemisphere. The equinox date can vary each year, so March 21st isn’t always the first day of spring (or autumn down under!).
The spring (or vernal) equinox happens when the Sun crosses the celestial equator, moving from south to north. This imaginary line in the sky sits directly above the Earth’s equator. On this day, both hemispheres receive roughly equal amounts of sunlight. While daylight hours have been increasing in the Northern Hemisphere since the winter solstice, the March equinox marks a turning point where many locations experience more daylight than darkness. Daylight will continue to increase in the north until the summer solstice in June. In the Southern Hemisphere, the opposite is true – daylight hours will decrease until the winter solstice.
The word “equinox” comes from Latin, meaning “equal night” (aequus – equal and nox – night). While not perfectly equal, day and night are almost the same length worldwide on the equinox.
Spring (and Autumn) can be defined in two ways: astronomically and meteorologically. Astronomically, spring begins on the spring equinox in the Northern Hemisphere, which can fall on March 19th, 20th, or 21st. Meteorologically, spring starts on March 1st and ends on May 31st in the Northern Hemisphere. This fixed-date system allows weather scientists to compare seasonal statistics more easily. In Australia, meteorological autumn runs from March 1st to May 31st.
While day and night are nearly equal on the equinox, they aren’t exactly so. True equality would only occur if the Sun were a single point of light and Earth had no atmosphere.
Tulips blooming in a garden, marking the arrival of spring.
A common folklore belief suggests that a raw egg can stand on its end on the equinox. While possible, balancing an egg is achievable on any day. Success usually depends on the egg’s shape and the surface texture.
The summer solstice, occurring between June 20th and 22nd, has the most daylight hours and is considered the “longest” day of the year in the Northern Hemisphere. For Australians, this is the winter solstice and the shortest day of the year.
Many cultures celebrate the spring (or autumn) equinox with festivals, marking new beginnings and nature’s renewal.
Ancient civilizations closely tracked the Sun’s path, using it as a natural clock and calendar. The Mayan pyramid at Chichen Itza in Mexico is a famous example. On the spring equinox, the sunlight creates the illusion of a serpent slithering down the steps, a phenomenon known as “the return of the Sun serpent.”
Spring (and Autumn) is celebrated with various poems, quotes, and sayings, reflecting the joy and renewal associated with the season.