The September Full Harvest Moon (2020)

September's full Moon is often the Harvest Moon. But not this year. Find out why.

Our September full Moon (typically known as the Harvest Moon) has an identity problem.

First, there is the confusion about just when it will occur. If you live in the western United States and Canada, it will arrive on Tuesday, September 1st. Pick up your local newspaper and on the weather page, and you likely will see, under phases of the Moon, that it is “full” on the 1st.

But if you live in the Central, Eastern, or Atlantic Time Zone, the moment when the Moon turns 100% full comes just after midnight on Wednesday, September 2nd at 12:22 a.m. for St. Louis and Chicago, and 1:22 a.m. for New York and Miami.

September Full Moon: What’s In A Name?

And then there is the problem as to what to call it. Each month, the full Moon is assigned a “traditional” name which are found in most almanacs and calendars and are related to Native American Algonquin and Iroquois tribes. See all the Moon names here for the year here.

The full Moon that arrives closest to the autumnal equinox is branded the Harvest Moon. Usually, we associate the Harvest Moon with September, although that is not always the case. Sometimes, if the full Moon occurs during the first week of September, we must wait until October for the Harvest Moon.

Between 1970 and 2050, there are 18 years when the Harvest Moon comes in October and wouldn’t you know it? This seemingly dysfunctional year of 2020 is one of those years.

The last time this happened was in 2017. On average, October Harvest Moons come at three-year intervals, although the time frame can be quite variable, and there can be situations where as many as eight years can elapse (the next such example will come in 2028).

An Early September Moon

This year we have an exceptionally early September Moon. So early, in fact, it comes before Labor Day (the unofficial end of summer). How can you have a Harvest Moon arrive before summer has wound down? It makes no sense!

So this year, the full Harvest Moon will come on Thursday, October 1st. And it will actually be the first of two full Moons in that month, the second will fall on Halloween, Saturday, October 31st. Read more on that here.

It does, however, make one wonder: If our September full Moon comes too early in the calendar to be called the Harvest Moon, then what do we call it?

It appears that based on some traditions we would call it the “Corn Moon.” This makes some sense, since at temperate latitudes corn is usually planted about three weeks after the last frost in spring. For many places that nearly coincides with Memorial Day. Corn requires up to 100 frost-free days to reach harvest depending upon variety and the amount of heat during the growing season. That would take us to around the end of August to early September. Hence, for a full Moon in early September it seems appropriate to brand it as a “Corn Moon.”

However, other authorities say something different. Guy Ottewell, who for over 40 years published his “Astronomical Calendar,” claims that a too-early September Moon is called the “Fruit Moon.”

How about tagging it as the “Hurricane Moon?” Hurricane activity traditionally reaches its peak in the early part of September. Or perhaps since the August full Moon is named for a sturgeon, extend this “fishy concept” into early September with a “Bluefish Moon?” — as any angler will tell you, bluefish are most prolific at this time of year.

The Harvest Moon Returns To September in 2021

In 2021, September’s full Moon will fall on September 20, 2021 and will be the full Harvest Moon, but it will be the last full Moon of the summer instead of the first full Moon of fall—yet still closest to the equinox.

Whatever you call it, get outside and enjoy it!

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Joe Rao

Joe Rao is an esteemed astronomer who writes for, Sky & Telescope, and Natural History Magazine. Mr. Rao is a regular contributor to the Farmers' Almanac and serves as an associate lecturer for the Hayden Planetarium in New York City.


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Love all and any articles about the Moom


Hey Joe – sorry about the criticism. Granny got hold of my phone and let loose. She used to be a journalist with New York Times before it went online and “downhill” as she laments. Great article and fun facts. Love the link especially. We love learning astronomy here! Keep it coming! I’ll keep my phone away from Gran! Kat


Joe – very interesting moon facts. Appreciate your efforts. I’m having a problem with internet writers today, though, and the problem is becoming very consistent unfortunately. Can you please share with your colleagues to please carefully proofread before submitting to the World Wide Web. It is clear that you did not and unfortunately becomes very distracting and then spoils the article for me. Please forgive me if I’ve offended, but it is just something that has been lost in our new internet culture, along with the apostrophe. Otherwise, thanks for the information.

Mary Ellen Birchenough

Will enjoy no matter the name!

Susan Wood

How about “September full moon? “. Lol

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