Here Comes Fall: Harvest Moon 2018 Rises Tonight!
With unseasonably warm summer temperatures persisting over much of the world this year, it seems hard to believe that this is the week of the Harvest Moon, the full moon nearest to the autumnal equinox.
Saturday, Sept. 22, was the first official day of autumn in much of the Northern Hemisphere, even though it will still officially be summer through the daylight hours. The moment of the equinox — the official end of summer and beginning of autumn — will not arrive until 9:54 p.m. EDT. East of the prime meridian, where the equinox occurs after midnight, the first day of fall will actually be on Sunday (0154 GMT, Sept. 23).
The moon will officially turn full two nights later, on Monday (Sept. 24), when it will reach the spot in the sky opposite (180 degrees) to the sun. That moment will occur at 10:52 p.m. EDT (0252 GMT on Sept. 25). The moon will slowly wane thereafter, making this upcoming week one that will be rich in moonlight. [The Moon: 10 Surprising Lunar Facts]
This year's version of the Harvest Moon falls in September, although on occasion, this branding can be conferred upon the October full moon. From 1970 to 2020, this calendrical oddity happens a dozen times and in fact happened just last year. The Harvest Moon can occur as early as Sept. 8 (as in 2014) or as late as Oct. 7 (as in 1987)
https://www.space.com/41913-harvest-moon-2018-september-rises-tonight.html