When Does Spring Start 2025? March 20 Equinox Date

Few calendar dates stir as much anticipation—and confusion—as the first day of spring. Many of us grew up circling March 21, but the official start in 2025 lands a day earlier, on March 20.

Astronomical spring start (N. Hemisphere): March 20, 2025 at 5:01 AM EDT ·
Meteorological spring start: March 1, 2025 ·
Southern Hemisphere spring start: September 22, 2025 ·
Spring equinox date range: March 19–21 annually

The difference between March 1 and March 20 reveals two competing definitions for spring’s start.

What is the first day of spring in 2025?

Astronomical spring start

• The vernal equinox in the Northern Hemisphere arrives on March 20, 2025 at 5:01 AM EDT (CBS News). At that precise moment, the center of the Sun crosses the plane of Earth’s equator, heading north (NASA Science).
• The same event happens at 09:01 UTC — for the West Coast, that’s 2:01 AM PDT (NASA Science).

Meteorological spring start

• Meteorologists and climatologists use a simpler system: spring begins on March 1 and lasts exactly three months (National Weather Service).
• This fixed calendar approach makes it easier to compare seasonal statistics across years.

The implication: you can celebrate two “first days of spring” — March 1 for weather watchers and March 20 for sky watchers.

When does the spring equinox happen in 2025?

Equinox date and time

• The March equinox occurs at 09:01 UTC on March 20, 2025 (NASA Science). That translates to 5:01 AM EDT / 2:01 AM PDT.
• The September equinox (which starts spring in the Southern Hemisphere) happens on September 22, 2025 at 19:19 UTC (NASA Science).

Day length

• On the vernal equinox, the Earth’s axis is neither tilted toward nor away from the Sun, giving nearly 12 hours of daylight and 12 hours of darkness at all latitudes (CBS News, citing the National Weather Service).

What this means: don’t expect exactly equal day and night — atmospheric refraction makes sunrise a few minutes earlier, so day length is slightly longer than night.

Is March 21 always the first day of spring?

Why the date changes

• The first day of spring can fall on March 19, 20, or 21 depending on the year (CBS News).
• Because Earth’s orbit takes 365.25 days, the equinox shifts by about six hours each year, with a leap day resetting the calendar.

Astronomical vs. meteorological definitions

• Astronomical spring is based on Earth’s 23.5° tilt and its orbit around the Sun. It begins at the exact moment of the vernal equinox (NASA Science).
• Meteorological spring divides the year into neat three-month blocks for consistent record-keeping (National Weather Service).
• The UK and many other countries use both definitions in different contexts (Royal Museums Greenwich).

The catch: while March 21 has become a cultural shorthand for spring’s arrival, it hasn’t been the actual equinox date since 2007 — and won’t be again until 2102.

Three items, one pattern: astronomical seasons follow celestial events while meteorological seasons follow the calendar for consistency.

The pattern: meteorologists prioritize comparability; astronomers keep faith with the sky. Neither is wrong — they just serve different purposes.

Timeline signal

• March 1, 2025 – Meteorological spring begins in the Northern Hemisphere
• March 20, 2025 – Vernal equinox (astronomical spring starts)
• June 20, 2025 – Summer solstice (summer begins) (CBS News)
• September 22, 2025 – Autumnal equinox (autumn begins) (NASA Science)
• December 21, 2025 – Winter solstice (winter begins)

“The vernal equinox marks the moment the sun crosses the celestial equator, heading north.”

TimeAndDate.com

“Meteorological seasons are based on the annual temperature cycle and are more closely aligned with the calendar.”

The Old Farmer’s Almanac

“In the UK we tend to use both definitions – astronomical for tradition and meteorological for official statistics.”

Royal Museums Greenwich

For anyone planning spring activities in 2025, the key takeaway is this: mark March 20 as the day the sun crosses the equator, but also remember that March 1 is when many forecasters treat spring as starting. Adjust your garden planting calendar and seasonal planning accordingly — or enjoy having two reasons to celebrate the end of winter.

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While many rely on the March 20 equinox as spring’s official start, understanding the meteorological spring definition helps explain why some calendars mark the season as beginning on March 1.

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