Harvest Moon

Everything You Need to Know About Monday Night's Harvest Moon

Wednesday also marks the Autumnal Equinox, the official start of fall

For a quiet weather pattern, it’s an exciting time in the sky – both the Full Harvest Moon and the Autumnal Equinox are this week!

The Harvest Moon reaches its fullest Monday evening, shortly after rising at 7:05 p.m. in a clear sky. With a large dome of high pressure – fair weather – anchored over the northeast, not only does dry air make for a clear sky, but it’s also made for some cool overnights and Monday night beneath the Harvest Moon will continue that trend with widespread low temperatures in the 40s.  

Of all our full moons in the course of a year, the Harvest Moon ranks among the most beloved we hear from our viewers about and that makes sense – it has a long, proud history in New England. 

The name, however, depends on what thread of history one chooses to pull. For instance, the “Harvest Moon” is believed to have originated in Europe as farmers harvested their crops toward the end of the growing season, but there was probably a bit more to it – usually the full moon rises nearly an hour later with each passing night, but this time of the year, that night-to-night lag slows a bit. Moonrise Sunday evening was 6:41 p.m., for example, full moonrise Monday evening is 7:05 p.m. and moonrise Tuesday evening will be 7:26 p.m., providing a bit more consistency to the moonlight cast upon fields ready for harvest. 

Here in New England, The Farmer’s Almanac notes the Native American name for this moon was the Corn Moon, likely for a similar reason that corn was harvested at this time of the year. In short, the Harvest Moon – or Corn Moon – has been a pivotal moon across the Northern Hemisphere for hundreds of years – likely much more than that – providing extra light for continued work at a time of year people across the hemisphere need it, and would have needed it even more prior to the advent of electric lights, ahead of the onset of the frost season.

On the heels of Monday evening’s Corn Moon comes Wednesday’s Autumnal Equinox – the “official” start of fall. Wednesday at 3:21 p.m. ET marks the start of the new season, but what exactly does this mean? 

In the world of meteorology, we define fall as September, October and November – starting on Sept. 1 – but astronomical autumn follows the mark of the equinox. 

Observed in both the spring and fall, the equinox marks the moment when the sun is exactly above the Equator, directly overhead there in the noon sky. The practical effect of the autumn equinox here at home in New England is more rapidly and noticeably decreasing day length, with daylight dropping at a rate of nearly 3 minutes per day, dropping below 12 hours on Sept. 26 and continuing to decline until our shortest day this coming Dec. 21 with 9 hours, 4 minutes and 35 seconds of daylight. 

Of course, our New England average temperature also drops in response to the loss of daylight, with high temperatures in someplace like Boston dropping a degree every three of four days until slowing at the start of December.

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