Spring 2025: the spring equinox explained
The March equinox has captivated human civilization for thousands of years, and it has even been tied to ancient mysteries -- yet there are still many misconceptions around the changing of the season.
AccuWeather’s Melissa Constanzer takes a look at what the vernal equinox is.
Spring has officially sprung in North America, bringing with it the promise of warmer days. At precisely 5:01 a.m. ET on Thursday, March 20, the sun's rays fell directly on the equator, marking the first official day of spring in 2025.
The spring equinox, also known as the vernal equinox, typically lands on March 20 or 21 and marks the beginning of astronomical spring, compared to what forecasters consider "meteorological spring," which began on March 1.
Two times each year, the Earth's rotation around the sun creates an equinox, kicking off the beginning of spring and autumn. But what exactly is an equinox, and what does it mean?
Bob Berman, an astronomer for Slooh, explained that the Earth is set on a tilt, and an equinox occurs when the Earth's tilt is directed in a way that the sun's most direct rays shine on the equator. This evenly distributes the sun's rays across the Earth's surface. The result is a day featuring around 12 hours of daylight followed by a night lasting about 12 hours everywhere around the globe.
Following the vernal equinox, the sun's rays become more focused on the Northern Hemisphere, with days growing longer and longer leading up to the June solstice. Meanwhile, nights become longer than days across the Southern Hemisphere as areas south of the equator experience the start of autumn.
The spring equinox occurs when Earth’s tilt aligns the equator with the sun, equalizing day and night length.
In comparison, solstices are when the Earth is tilted in a way where one part of the Earth is hit directly with sunlight. For example, summer is warmer due to the Earth being tilted so the hemisphere is pointing toward the sun, receiving the most amount of direct sunlight and warming the surface.
As the Northern Hemisphere welcomes spring today, the Southern Hemisphere is marked with the first day of autumn.
"There's no 'thing' that happens on the first day of spring, summer or winter meteorologically, but there is something that happens on the first day of the seasons calendar-wise, and those are the equinoxes and solstices," Berman told AccuWeather. However, once the equinox passes, the days begin to become warmer as the sun moves in a more direct position over the hemisphere.
Civilizations have been conscious of equinoxes for thousands of years, which allowed them to establish directions. A study of ancient Egyptian architecture uncovered a technique that may explain the precision of the Great Pyramid's alignment to the north, east, south and west. The proposed technique correlates directly to the rotation of the Earth and its position to the sun.
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