What Is the Harvest Moon?

Shine On, Harvest Moon! Facts and Folklore

By Fred Schaaf
September 16, 2021
Full Harvest Moon - Grains

In 2021, the Harvest Moon rises on Monday, September 20! The Moon will appear full for about three days around this time, from Sunday morning through Tuesday morning. Why does this phenomenon happen? Learn more—and shine on, Harvest Moon!

When Is the Harvest Moon?

This year, the brilliant Harvest Moon will appear in the evening of Monday, September 20, reaching peak illumination at 7:54 P.M. EDT.

One thing that sets the Harvest Moon apart from other full Moon names is that it’s not associated with a specific month, as the others are. Instead, the Harvest Moon relates to the timing of the autumnal equinox (September 22, 2021), with the full Moon that occurs nearest to the equinox being the one to take on the name “Harvest Moon.” This means that the Harvest Moon can occur in either September or October, depending on how the lunar cycle lines up with the Gregorian calendar.

The Harvest Moon does typically occur in September, taking the place of the full Corn Moon. However, it occasionally lands in October instead, replacing the full Hunter’s Moon.

Why Is it Called the Harvest Moon?

For several evenings, the moonrise comes soon after sunset. This results in an abundance of bright moonlight early in the evening, which was a traditional aide to farmers and crews harvesting their summer-grown crops. Hence, it’s called the “Harvest” Moon!

There are just a little over 12 complete Moon cycles every year, on average (there being about 29.53 days in a synodic month). The Harvest Moon isn’t like the other Moons.

  • Usually, throughout the year, the Moon rises an average of about 50 minutes later each day. 
  • But for the few nights around the Harvest Moon, the Moon seems to rise at nearly the same time: just 25 to 30 minutes later across the northern USA, and only 10 to 20 minutes later farther north in Canada and Europe.

Additionally, the Harvest Moon rises at sunset and then will rise very near sunset for several nights in a row because the difference is at a yearly minimum. It may almost seem as if there are full Moons multiple nights in a row!

Hay bales

More About the Harvest Moon

If interested, here is more detailed information about the Harvest Moon. (Warning: Scientific explanation below!)  

The Moon’s orbital motion (combined with the larger orbit of the Earth around the Sun) carries it farther eastward among the constellations of the zodiac from night to night. At any one moonrise, the Moon occupies a particular place on the celestial sphere (the great dome of the heavens), but when the Earth turns toward that point 24 hours later, the Moon has moved off to the east about 12 degrees, and it takes an average of 50 minutes longer for the Earth to rotate toward the Moon and for the Moon thus to “rise.” Think of it as a giant Slinky in which each loop, representing one lunar orbit of the Earth, advances the orbit a bit farther along the spiral path. The result of all this is that the Moon doesn’t rise at the same time everyday.

But around the date of the Harvest Moon, the Moon does rise at about the same time for several days in a row. Why? Remember that the zodiac is the band of constellations through which the Moon travels from night to night. The section of the zodiac band in which the full Moon travels around the start of autumn is the section that forms the most shallow angle with the eastern horizon. Because the Moon’s orbit on successive nights is more nearly parallel to the horizon at that time, its relationship to the eastern horizon does not change appreciably, and the Earth does not have to turn as far to bring up the Moon.

The Moon may rise as little as 23 minutes later on several nights before and after the full Harvest Moon (at about 42 degrees north latitude), which means extra light at peak harvest time near autumn. By the time the Moon has reached last quarter, however, the typical 50-minute delay has returned.

At the start of spring, the opposite applies. The full Moon is in the section of the zodiac that has the steepest angle with respect to the eastern horizon. For several days bracketing the full Moon nearest the vernal equinox, the delay in moonrise is as much as 75 minutes (at 42 degrees north latitude).

Full moon and clouds

Here is another way of expressing what happens with the Harvest Moon: It is in this part of the zodiac that the Moon’s eastward (orbital) motion has its largest northward component. For observers in Earth’s Northern Hemisphere, the farther north an object is in the heavens, the longer an arc it makes across the sky, and the longer a time it is visible above the horizon. Thus, to say that the Moon is getting rapidly farther north each night around the time of the Harvest Moon is to say that, for northern latitudes on Earth, it will keep rising distinctly earlier than would otherwise be expected—nearly the same time as the night before.

How nearly the same is “almost the same time” each night? This varies with latitude, for the farther north you are, the shallower the angle of the zodiac is with respect to your horizon. In most of the United States and southern Canada, the Harvest Moon rises 25 to 30 minutes later each night. The effect is less noticeable the farther south you go. But going north makes the Harvest Moon more extreme.

According to astronomy author Guy Ottewell, the idea of the Harvest Moon originated in Europe (average latitude about 50 degrees north), where the Harvest Moon rises only ten to 20 minutes later each night. It must have seemed a boon that just when days were getting rapidly shorter and the Sun seemed to go down all too soon, the Harvest Moon arrived to extend the hours that harvesting could be done.

Low full moon

Chinese Harvest Moon Traditions

As a final note, I should add that it is not just Western civilization that has given special importance to the Harvest Moon. For Chinese people everywhere, this full Moon is the occasion for the Festival of the August Moon (the “August” is through a calendar discrepancy) or Mid-Autumn Festival (in some cultures, the equinoxes and solstices have been considered the middle of the seasons). This festival is celebrated with joyful games and the eating of “Mooncakes.”

I remember vividly being invited to one such celebration and singing songs and playing my guitar to a circle of friendly faces in the light of the rising Harvest Moon.

Learn More

Ever notice that the low-hanging Moon looks especially big near the horizon? It isn’t really significantly bigger. Learn more about this trick of the eye called the Moon Illusion.

Find out what your Moon phase is tonight and when the next full Moon is.


Reader Comments

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Why a warning?

I love the Old Farmer's Almanac! My grandmother always had a copy on the table beside of her chair. We only got to visit with her a couple of times a year but I would read it cover to cover! I learned so much from it. I am wondering why you have a box "Warning, scientific explanation below"? Thank you!


The Editors's picture


Thank you for reading our almanac! We’re happy to hear that you’ve enjoyed its contents. That warning was our tongue-in-cheek attempt at humor!

Harvest moon

This year Halloween fell on a weekend.
Time to tie the stalks and sell our gourds and pumpkins.
The bees are on the swarm for the end of their season.

harvest moon

I can remember many a night on the farm doing beans we would talk about the lore of the harvest moon. Sometimes beans were already done and we were starting corn which could run til the wee hours of the morning. But we always had that full moon. Those were good times with good people and hard work. You knew what a long days work was when it was over, until the next day. then you started up again.

Harvest Moon

Love this stuff, Large family Farm Northern Kentucky.
This is my favorite time of year and I have always noted the "Moon" in my life.
While I understand the relevance of the harvest moon, I did not know that it was at least as relevant to the Chinese (really Duhhhh).
We (Westerners) have a tradition of names, What is the name tradition for the Chinese, "Moons"?

Harvest Moon; Praying for Positive Promises from God to Harvest

The details of the Harvest Moon was brought to my attention late yesterday. Opening my back door I noticed the moon positioned in the northeast with a powerful illuminiation. As I returned to my computer and telephone conversation I mentioned how beautiful the moon was shining. At that premise moment, the person on the other end of the phone shared with me that it was the Harvest Moon. I had never heard of the Harvest Moon, but I was instructed to make a wish and several wishes. Instead, I shall pray as ask God to release blessings, miracles, and healings categorically into my life. Afterall, it was God that created the moon; Genesis 1:14,16, Psalm 8:3, and Isaiah 30:26.

Harvest Moon, harvesting crops

So the harvest moon would mark the time between it and the fall equinax (Sept. 23 ?) for harvesting crops. Is this because there is not enough daily light to grow efficiently anymore or because the moon offers the ability to work late into the night and you hope your crops are ready to harvest?


I learned about whippoorwills from my father playing guitar (My Blue Heaven), and it's how I came to know about harvest moons, too! => Leon Redbone - Shine On Harvest Moon

2018 Harvest Moon

Won't be able to see it this year. Clouds and rain are in the forecast for most of this week. Temps and humidity are down, so there is that.

all informative

If I were to give a score between one and ten; you would get ten plus.

Slooh and the monthly Full Moon shows?

Does the Old Farmer's Almanac still partner with Slooh to do the full-moon streaming programs??? I haven't seen this in a while. I guess I can go directly to Slooh, but there were speakers on this video streaming show from the Old Farmer's Almanac, talking about both the scientific and the folkloric aspects of every month's full moon. What's the story, Old Farmer's Almanac? Do you still partner with Slooh???
Thanks in advance.

Slooh and the Almanac

The Editors's picture

Thank you for your enthusiasm for the SLOOH programs, Christine. We participated with the SLOOH folks for much of 2016, in the way that you describe—offering facts and lore about each month’s full Moon. In many shows, we had an editor, live-streaming from our offices, as well as our astronomer Bob Berman, live-streaming from his home or planetarium. The most recent show was in August, on the occasion of the Mini Strawberry Moon.

The partnership is still in place, but Almanac appearances/participation are as the producers/programmers need. We join in whenever we are asked. Thank YOU again for asking about it.

Harvest Moon

Very interesting, I'm ashamed to admit that I never really took an interest in such matters, it appears the older I have become, the more interest I have in such beautiful things, what's the saying, "youth is wasted on the young" funny !!!!

harvest moon article

Obviously only talking about the northern half of the Earth

Can you write this stuff so

Can you write this stuff so idiots like me can understand?

harvest moon

hi james, you are absolutely right, i wish i could understand it, it sounds very interesting. have a nice day, by the way, i am from austria

i like cakes - maybe

i like cakes - maybe mooncakes....otherwise very intersting all....!

well- even deeper, tis the

well- even deeper, tis the time of transition, the harvest as highest tide too, thus its sedna's birthday among the northern artic folk, she who has birth'd the sea, she who calls toward and from the underworld, this gate of change is celebrated too as a time to invoke mercy(catholic as our day that belongs to the honoring of Our Lady of Mercy), also as yom Kippur- day of atonement,the day in the pagan cosmology as the death and mourning of Demeter for Persephone, who descends to the underworld in contract with Hades, the great god of the dead, who wooed and wed her astride his black stallion, representing all the wildness which we cannot ever control, the changed to the dark of evil with our current entrance to the season of all hallows eve, halloween, but which otherwise is the day when the veil is thinnest to the other world, or under world! SO, this is a moon of great promise, great fate and fear and all hope. Happy harvest moon all!

Well said...Blessed Be.

Well said...Blessed Be.

Is there a Mooncake recipe?

Is there a Mooncake recipe?