The Harvest Moon Peaks Monday Over Washington: What To Know

SEATTLE — If you need another sign that summer is coming to an end in Washington, just look to the skies Monday evening as the 2021 full harvest moon rises into the night skies over Puget Sound. After a weekend of fall-like weather, complete with several bouts of heavy rain and a few thunderstorms, forecasts show Western Washington skies clearing with plenty of time to take in the celestial sight.

This year’s harvest moon falls just two days before the autumn equinox on Wednesday. Here that means the moon will reach peak illumination in the sky Monday at 4:54 p.m. — not exactly ideal since the sun will still be shining, but it'll stay plenty bright through the night.

Depending on the year, the full harvest moon usually happens up to two weeks before or after the autumn equinox, according to EarthSky.org. It’s either the last full moon of summer or the first full moon of fall.

The harvest moon typically occurs in September, taking the place of the full corn moon. However, if it happens in October, it replaces the full hunter’s moon.

The origin of the harvest moon can be linked to the Native Americans, who looked to this full moon each autumn as a sign it was time to harvest their crops, according to the Farmers’ Almanac. For a few days before and after it reaches its fullest point, the moon hangs in the sky like a glowing lantern, prolonging the light well after sunset.

Some trace the moon’s moniker back to farmers, according to EarthSky.org. In the days before tractor lights, the harvest moon helped farmers gather their crops as daylight hours lessened, illuminating the fields through the night.

Is the harvest moon bigger or brighter than other moons? It depends.

The harvest moon’s distance from Earth is different each year. Last year, the harvest moon was the second-smallest full moon of 2020, according to EarthSky.org. In 2019, the harvest moon was actually a mini-moon, or the most distant and smallest-appearing full moon of the year 2019. In 2015, however, the harvest moon was the year’s closest and largest-appearing supermoon.

The harvest moon is known to take on an orange hue as it rises. This happens because when you look to the horizon rather than up and overhead, you’re looking through a greater thickness of Earth’s atmosphere.

Patch Editor Megan Verhelst contributed to this report.