Spring equinox 2025 is here: What to know about the change of seasons
This story was updated to add new information.
Spring has sprung, bringing warmer days and blooming flowers.
Thursday is the first day of spring, or the vernal equinox, in the Northern Hemisphere. During an equinox, the center of the sun is on the same plane as the equator. After the vernal equinox in March, the Northern Hemisphere tilts toward the sun until the June solstice, when the sun begins to migrate back south.
When is the spring equinox?
At precisely 5:01 a.m. ET on Thursday, the sun's rays fall directly on the equator, marking the first official day of spring. Meteorologists consider March 1 the start of spring.
An equinox occurs twice a year. The autumnal equinox occurs in September – when the Earth's axis is tilted neither toward nor away from the sun, resulting in roughly 12 hours of daylight and 12 hours of darkness almost everywhere on the planet.
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Day and night aren't exactly 12 hours on the day of the equinox because the Earth's atmosphere refracts, or bends, light in an optical illusion that brings more daylight than there really is. Because of this, the date when day and night are of exactly equal length usually comes a few days after the spring equinox.
Spring means longer days than nights
The sun is directly above the equator during both equinoxes. We experience the longest day of the year on the summer solstice. That's when the Northern Hemisphere is at its greatest tilt toward the sun, causing the sun to appear at its highest point, according to NOAA's National Weather Service.
This bending of sunlight "causes the sun to appear above the horizon when the actual position of the sun is below the horizon," the weather service says. Because the sun takes longer to rise and set the closer you are to the poles, the day gets a little longer as your latitude increases.
The shortest day of the year occurs on the winter solstice, when the Northern Hemisphere reaches its maximum tilt from the sun, causing the sun to appear at its lowest point in the sky.
CONTRIBUTING Doyle Rice