When Is September’s Full Moon, and What Time Can I See It?


The moon is currently approaching its “full” phase. But when exactly will September’s full moon appear?

While the moon will appear full to most observers from September 9 to 11—Friday through Sunday—technically, it only turns full at a specific moment.

In this case, the moon will reach peak illumination at 5:59 a.m. Eastern Time, or 2:59 a.m. Pacific Time, on Saturday, September 10, according to the Farmers’ Almanac.

For anyone who wants to observe the moon at the exact time it turns full, this is the moment to do so.

Full moons are a lunar phase that occur roughly once every month when our natural satellite is located opposite the sun in space, with the Earth in between. During the full moon phase, the side of the moon that faces toward us is completely illuminated by the sun’s light, appearing like a perfect circle in the sky.

A Harvest Moon above New York
A Harvest Moon sets behind the Statue of Liberty on September 20, 2021 in New York City. The Harvest Moon can fall in September or October.
Gary Hershorn/Getty Images

As a result, every full moon rises around the time of sunset and sets around the time of sunrise.

The full moon in September, 2022, can be referred to by the name “Harvest Moon”. But this does name not always apply to a full moon in this month.

Most of the traditional names for the full moons are associated with a specific month. For example, the term “Pink Moon” is always used to refer to a full moon in April.

But a Harvest Moon can appear either in September or October, depending on how the lunar cycle lines up with the Gregorian calendar. The name is given to whichever full moon occurs closest to the Northern Hemisphere’s autumnal equinox, which always falls between September 21 and 24.

On most occasions—two out of every three years—the Harvest Moon arrives in September. But in some years, the closest full moon to the fall equinox occurs in October.

In situations where the Harvest Moon falls in October, the full moon in September is often referred to as the Corn Moon.

The September equinox marks the beginning of fall, according to the astronomical definition of the seasons, in the Northern Hemisphere.

During this equinox, the sun shines directly over Earth’s equator, and the length of day and night is roughly equal.

The reason we have equinoxes—as well as solstices—is that the Earth’s axis is tilted at an angle of around 23.4 degrees relative to the plane of its orbit around the sun. During the Northern Hemisphere’s summer solstice, the Earth’s pole is tilted toward the sun. But during the equinoxes, the North Pole is tilted neither toward or away from the sun.