Meteorological Seasons: When Spring Really Begins
Winter's over? Sort of. We explain why meteorologists have already moved on to the spring season and how it differs from our calendar.
Quick Reference: Meteorological Seasons
- Spring: March, April, May (begins March 1)
- Summer: June, July, August
- Fall: September, October, November
- Winter: December, January, February
- Astronomical spring 2026: begins at the spring equinox, March 20
- Why the split: meteorologists group whole months so weather records stay tidy and easy to compare.
Does spring start on March 1? By the meteorological calendar, it does. The forecaster on your evening news works from a different calendar than the one hanging on your kitchen wall, which is why you may hear that winter has ended weeks before the last snowbank melts. Here is how meteorological seasons work, how they differ from the astronomical seasons you grew up with, and why weather watchers keep two calendars at all.
Meteorological Seasons Explained
Meteorologists define the seasons in a different way than astronomers. Each of the seasons is defined by the most severe of the months in a season. For winter, that is December, January, and February. Group the year into four neat blocks of three whole months each and you have the meteorological calendar. The four meteorological seasons are broken up like this:
- Spring: March, April, May
- Summer: June, July, August
- Fall: September, October, November
- Winter: December, January, February
Because each season is a fixed set of months, the start dates never move. Meteorological spring always opens on March 1, summer on June 1, fall on September 1, and winter on December 1. No timetable to check, no minute to mark, the same first-of-the-month date every year.
Astronomical Seasons: Sun, Solstice, and Equinox
Astronomers, on the other hand, define the change of seasons by the position of the Sun. “Winter” in the Northern Hemisphere is defined by when the noontime Sun reaches its farthest point south in the sky, or when the Sun’s rays shine down from a point directly overhead as seen from the tropic of Capricorn (latitude 23.5 degrees south), known as the winter solstice. That happens on December 21 (or 22, depending on the year). It continues as such until the direct solar rays shine down on the equator at the vernal, or spring equinox, on March 20th in 2026. The date and time of spring changes from year to year.
The same solar geometry sets the other two turning points. The summer solstice around June 21 marks the astronomical start of summer, and the fall equinox around September 22 opens autumn. Because the Sun does not keep a tidy first-of-the-month schedule, these dates drift a day or so each year, which is exactly the wrinkle that led weather scientists to keep a second calendar.
Meteorological vs. Astronomical Seasons at a Glance
The two systems land within about three weeks of each other, but they never quite match. One counts by the calendar month, the other by the Sun. Here is how the four seasons stack up side by side.
| Season | Meteorological (whole months) | Astronomical (Sun’s position) |
|---|---|---|
| Spring | March 1 to May 31 | Spring equinox, about March 20 |
| Summer | June 1 to August 31 | Summer solstice, about June 21 |
| Fall | September 1 to November 30 | Fall equinox, about September 22 |
| Winter | December 1 to February 28 or 29 | Winter solstice, about December 21 |
Why Meteorologists Split the Year Into Whole Months
The reason is record-keeping. Weather scientists compare one year against the last, and against the long run of years before it, so they need seasons that begin and end on the same date every time. Whole calendar months make the math clean: a season is simply three months of daily highs, lows, rain, and snow added up and averaged. Shifting solstice and equinox dates would leave the bookkeeping a day or two off from one year to the next.
The National Oceanic and Atmospheric Administration (NOAA), the federal agency that tracks the nation’s climate, explains that its centers use the meteorological seasons precisely because whole months make statistics and long-term comparisons more consistent. You can read the agency’s own plain-English breakdown of meteorological versus astronomical seasons at the National Centers for Environmental Information. It also happens to line the seasons up more closely with the temperature cycle most of us actually feel, since the coldest stretch of the year usually falls across December, January, and February rather than after the solstice.
In Short
In short, the seasons you are familiar with, by the calendar, are “astronomical,” and the seasons that your meteorologist chats about on the evening news are “meteorological.” So to them, spring begins March 1st. Neither one is wrong. They are two ways of slicing the same year, one built for the sky and one built for the record books.
Weigh In!
What do you think: should December 1st be the official start of winter and March 1st be the official start of spring? Whichever calendar you keep, do what works for how you plan your own year. Share your thoughts in the comments below.
Meteorological Seasons: Frequently Asked Questions
What are the meteorological seasons?
The meteorological seasons split the year into four blocks of three whole months each: spring is March, April, and May; summer is June, July, and August; fall is September, October, and November; and winter is December, January, and February. Each season starts on the first of the month, so the dates never move.
When does meteorological spring start?
Meteorological spring begins on March 1 every year. That is several weeks before astronomical spring, which arrives at the spring equinox on March 20 in 2026. If your local forecaster says spring has started while there is still snow on the ground, the meteorological calendar is the reason.
How are meteorological seasons different from astronomical seasons?
Meteorological seasons are grouped by calendar months, so they start on the same date every year. Astronomical seasons are set by the position of the Sun, marked by the solstices and equinoxes, so their start dates drift by a day or so from year to year. The two systems usually fall within about three weeks of each other.
Why do meteorologists use whole months for the seasons?
Whole months keep weather records consistent. When every season begins and ends on a fixed date, scientists can add up and average temperature, rain, and snow the same way every year and compare one year against the next. The National Oceanic and Atmospheric Administration uses this system for exactly that reason.
When does astronomical spring begin in 2026?
Astronomical spring begins at the spring equinox on March 20 in 2026, when the Sun’s direct rays shine down on the equator. The exact date and time shift slightly from year to year, landing on March 19, 20, or 21 depending on the calendar.
Which season definition is correct?
Both are correct. They are simply two ways of dividing the same year, one built around the Sun’s path and one built around the record books. Use whichever fits how you plan. Gardeners and stargazers often watch the solstices and equinoxes, while forecasters and climate scientists count by whole months.
This article was published by the Staff at FarmersAlmanac.com. Any questions? Contact us at questions@farmersalmananac.com.
- Farmers' Almanac Staff
- Farmers' Almanac Staff
- Farmers' Almanac Staff
- Farmers' Almanac Staff
I believe the meteorology of whether is backwards.
I love spring because Flowers Bloom.
Animals Return. …
Fruits and Vegetables are Abundant. …
Moods Improve. …
Vitamin D. …
Fresh Air! …
Temperatures Become Pleasant. …
More Daylight. In Spring, days get longer and nights get shorter, providing us with more hours of daylight! …
In Denver, spring comes sometime between March 15 and July 1st…..she can be joyful or very surly.
Astrological timing
I have went by meteorological seasons for about 10 years now and for me they make sense. In my neck-of-the-woods it is already cold by December 1st and warming up by March 1st.
Yes I agree with your dates . We wish they would leave the clock alone .Never mind changing it , in Oct and March ..Best regards.
In the land of Oz they use the Meteorologist seasons. according to some cyber-friends I have from Australia
I would refrain from deeming anything Mother Nature does, by nature, as “official”. Humans have no hand in the matter, and so do not establish, “officialize”, naturally occurring phenomena. Makes sense to me anyway.
Good point, Dom! She’s always in charge.
Depends on the local climate really. Here in Northern Illinois, I feel like December is commonly still nice enough to be considered the end autumn, and March is commonly still cold and snowy enough to be considered still winter.
Early spring please