When is the First Day of Fall? Autumnal Equinox 2024 (2024)

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 andfolklore.

When Is the First Day of Fall? The AutumnalEquinox?

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 momentworldwide.

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 yourlocation.

What Is the AutumnalEquinox?

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

What Is anEquinox?

During an equinox, the Suncrosses what we callthe “celestial equator”—an imaginary extension of Earth’s equator line into space.The equinox occurs precisely whenthe Sun’s center passes through thisline.

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 thereverse.

After the autumnal equinox, days become shorter than nights as the Sun continues to riselater and nightfall arrives earlier. This ends with thewinter solstice, after which days start to grow longer onceagain.

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 thisbelow.)

The Harvest Moon & the FallEquinox

One of our favorite piecesof 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 isthat?

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

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 arow!

An Astronomical MoonName

The Harvest Moon is one of only two Moon names that areastronomical termsand aren’t tied to one specific month. Becauseit’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 orNovember.)

FallWeather

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

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 todrop.

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

FallFoliage

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 aboutautumn leaves.

Fall Equinox FAQs

Q: Are Day and Night Perfectly Equal on theEquinox?

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

On the equinox, the center of the Sun is indeed above the horizon for 12 hours. However, “sunrise” is said to beginwhen 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 thannighttime.

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 aswell.

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

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 12:08hours.

See our Sunrise/set calculator for day lengthin YOURarea.

Q: Is the Autumnal Equinox Really the First Day ofFall?

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 tothe 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 SouthernHemisphere).

Q: Can You Balance An Egg On theEquinox?

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 factsfrom Almanac astronomer BobBerman.

Signs ofFall

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 forparents!

Trees snapping and cracking in the autumn indicate dryweather.

Fall also brings some wonderful holidays, includingHalloween 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 precioussleep!

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 pumpkinsand corn mazesabound.

Football season is warming up, and so is sweaterweather.

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 ourSun!

Of course, you canyou can easily notice the later dawns and earlier sunsets. See our sunrise/set toolfor yourarea!

Ancient AutumnTraditions

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

• At Machu Picchuin Peru, an ancient stone monument called Intihuatana—which means “Hitching Post of the Sun”—serves as asolarclock to mark the dates of the equinoxesandsolstices.
• In Mexico, the Mayans built a giant pyramid called ChichenItza. On the equinoxes, it looks as if a snake made of light slithers down the pyramid’ssteps.
• In England, Stonehenge was also built with the equinoxes and solstices inmind.

See Five Ancient Sites Aligned With the Equinoxes and Solstices.

EnjoyAutumn!

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

To learnmore about allfour seasons and see when they begin, see the First Day of Seasons.