When is the First Day of Fall? Autumnal Equinox 2024

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Facts, Folklore, and Everything You Need to Know About the Fall Equinox

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Welcome fall! The autumnal equinox—the September equinox or the fall equinox—arrives on Sunday, September 22. Not only do temperatures drop, but plant life slows down, and so do we. Read about the first day of fall, plus some fun facts and folklore.

When Is the First Day of Fall? The Autumnal Equinox?

The fall equinox and the first day of autumn arrives on  Sunday, September 22, 2024, at 08:44 A.M. EDT in the Northern Hemisphere. The equinox occurs at the same moment worldwide.

Autumnal Equinox Dates
YearAutumnal Equinox (Northern Hemisphere)Autumnal Equinox (Southern Hemisphere)
2024Sunday, September 22Tuesday, March 19
2025Monday, September 22Thursday, March 20
2026 Tuesday, September 22Friday, March 20
2027 Thursday, September 23Saturday, March 20

Note: Dates listed above are based on Eastern Time (UTC-5). Due to time zones, the date of the equinox may differ by +/- one calendar day in your location.

What Is the Autumnal Equinox?

The autumnal equinox is an astronomical event that marks the start of autumn (or “fall”). In the Northern Hemisphere, the autumnal equinox occurs in September; in the Southern Hemisphere, it occurs in March. 

What Is an Equinox?

During an equinox, the Sun crosses what we call the “celestial equator”—an imaginary extension of Earth’s equator line into space. The equinox occurs precisely when the Sun’s center passes through this line.

For those in the Northern Hemisphere, when the Sun crosses the equator going from north to south, this marks the autumnal equinox; when it crosses from south to north, this marks the vernal equinox. In the Southern Hemisphere, it’s the reverse.

After the autumnal equinox, days become shorter than nights as the Sun continues to rise later and nightfall arrives earlier. This ends with the winter solstice, after which days start to grow longer once again. 

The word “equinox” comes from Latin aequus, meaning “equal,” and nox, “night.” On the equinox, day and night are roughly equal in length. (See more about this below.)

covered bridge in the fall, first day of fall, first day of autumn
Foliage makes fall such a special season!

The Harvest Moon & the Fall Equinox

One of our favorite pieces of trivia surrounding the autumnal equinox involves its relationship with the full Moon. Curiously, the full Moon that occurs nearest to the autumnal equinox is always called the ”Harvest Moon!” Why is that?

Surprise, surprise: it has to do with farming! Around the fall equinox, the full Moon rises around sunset for several nights in a row, traditionally providing farmers with just enough extra light to finish their harvests before the killing hard frosts of fall set in.

Typically, the Moon rises about an hour later each night, but around the time of the fall equinox, the angle of the Moon’s orbit and the tilt of the Earth line up just right and cause the Moon to rise only about 20 to 30 minutes later each night for several nights in a row!

An Astronomical Moon Name

The Harvest Moon is one of only two Moon names that are astronomical terms and aren’t tied to one specific month. Because it’s always the full Moon nearest to the equinox called the “Harvest Moon,” either September or October’s full Moon can take on the name. (The other astronomical Moon name is the Hunter’s Moon, which is the full Moon that directly follows the Harvest Moon. It can occur in either October or November.)

Harvest moon with people standing in front

Fall Weather

It is the summer’s great last heat, 
It is the fall’s first chill: They meet. 
–Sarah Morgan Bryan Piatt

Another definition of fall is “nights of below-freezing temperatures combined with days of temperatures below 70 degrees Fahrenheit (21°C)”. From here on out, the temperatures begin to drop.

→ Find 12 months of long-range weather predictions in the latest edition of The Old Farmer’s Almanac!

Fall Foliage

Note that fall foliage isn’t due to current weather conditions. This is a common misconception. Leaves change color because of the amount of daylight and photosynthesis. Learn more about autumn leaves.

Japanese maple leaf in fall

Fall Equinox FAQs

Q: Are Day and Night Perfectly Equal on the Equinox?

A:  Some say that during an equinox, day and night are equal. Well, not exactly. It depends on where you live.

On the equinox, the center of the Sun is indeed above the horizon for 12 hours. However, “sunrise” is said to begin when the upper edge of the Sun’s disk becomes visible above the horizon (which happens a bit before the center rises) and ends when the entire Sun has set. In this case, daylight is still a bit longer than nighttime. 

Not only that, but the Sun is actually visible when it is below the horizon, as Earth’s atmosphere refracts the Sun’s rays and bends them in an arc over the horizon. Yes, you can see the Sun before the edge actually reaches the horizon! This causes daylight to be longer than 12 hours as well.

However, they are very close to equal (the total lengths may differ by only a few minutes). 

Did you know our rise/set tool now provides day length? In Dublin, New Hampshire, USA—home of The Old Farmer’s Almanac—our day length on the equinox is 12:08 hours.

See our Sunrise/set calculator for day length in YOUR area.

Q: Is the Autumnal Equinox Really the First Day of Fall?

A: Based on the astronomical definition of seasons, yes, the autumnal equinox does mark the first day of fall. Astronomical seasons are based on the Sun’s position in the sky. According to the meteorological definition of seasons, which is based on temperature cycles and the Gregorian calendar, the first day of fall is usually considered to be September 1 in the Northern Hemisphere (March 1 in the Southern Hemisphere).

Q: Can You Balance An Egg On the Equinox?

A: There’s an old wives’ tale that you can stand an egg on its end of the equinox. Well, yes, it’s true (and fun to try). But it’s possible not only on the equinox. See more about equinox facts from Almanac astronomer Bob Berman.

autumn woods
Foliage is one of the most beautiful signs of fall!

Signs of Fall

What are your local signs of fall? In many regions of the Northern Hemisphere, the landscape silently explodes with vibrant colors of red, yellow, and orange. The leaves begin to drop off the trees, providing endless hours of jumping into leaf piles for kids and raking them back up for parents!

Trees snapping and cracking in the autumn indicate dry weather.

Fall also brings some wonderful holidays, including Halloween and Thanksgiving, which carry us through the season until temperatures begin to drop, nights begin to get longer, and all the woodland critters start storing up for the long haul of winter

And don’t forget about the end of Daylight Saving Time, when we “fall” back, setting our clocks back one hour and regaining an hour of precious sleep!

Plants and trees are slowing down to get ready for the colder season ahead as sunlight decreases. In the garden, asters and chrysanthemums bloom beautifully as orange pumpkins and corn mazes abound.

Football season is warming up, and so is sweater weather.

Also, notice the arc of the Sun across the sky each day as it starts shifting south. Birds and butterflies migrate along the path of our Sun!

Of course, you can you can easily notice the later dawns and earlier sunsets. See our sunrise/set tool for your area!

Purple Aster
Aster flowers

Ancient Autumn Traditions 

The fall equinox has been a day of celebration for cultures since ancient days. People tracked the transitions of the Earth’s journeys around the Sun.

  • At Machu Picchu in Peru, an ancient stone monument called Intihuatana—which means “Hitching Post of the Sun”—serves as a solar clock to mark the dates of the equinoxes and solstices.  
  • In Mexico, the Mayans built a giant pyramid called Chichen Itza. On the equinoxes, it looks as if a snake made of light slithers down the pyramid’s steps.
  • In England, Stonehenge was also built with the equinoxes and solstices in mind.

See Five Ancient Sites Aligned With the Equinoxes and Solstices.

Enjoy Autumn!

Wishing a colorful, cool, cozy autumn to all our Almanac readers. Tell us your favorite things about the fall season below!

To learn more about all four seasons and see when they begin, see the First Day of Seasons.

About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann