According to the Old Farmers Almanac:
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!
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.
There are many traditions from around the world associates with the Harvest Moon. If interested the Almanac list many. Tonight I plan on starting my own. I am going to buy a Moon Pie at Cracker Barrel, go to the beach and watch the moon rise. Sounds like a plan!