Why 2025's Harvest Moon is a rare October full moon

 Our next full moon will occur on Oct. 6, and it will be a somewhat special one for those living in the Northern Hemisphere in that it will also carry the title of "Harvest Moon." The moon officially turns full when it reaches that spot in the sky opposite (180 degrees) to the sun in the sky and this moment will occur on Tuesday, Oct. 7 at 03:48 GMT (which corresponds to 11:48 p.m. EDT on Oct.6, or 8:48 p.m. PDT).

But it also turns out that this full moon is the one that comes closest on the calendar to the September equinox. In 2025, this circumstance comes later than usual, into the month of October, as opposed to the more traditional month of September. Full moon in September came on Sept. 7 and occurred 15.006 days prior to the autumnal equinox. The full moon of Oct. 6 occurs 14.395 days after the equinox, or 14 hours and 39 minutes nearer to the equinox than September's full moon.

It seems that most people are under the impression that the Harvest Moon remains in the night sky longer than any of the other full moons we see during the year, but that's not so. It's the full moon occurring nearest to the winter solstice that stays above the horizon the longest, at mid-northern latitudes in excess of 15 hours. What sets the Harvest Full Moon apart from the others is that it rises about the time the sun sets, but more importantly, at this time of year, instead of rising its normal average 50 minutes later each evening, the moon seems to rise at nearly the same time each night. In fact, this unusual circumstance, a full (or nearly full) moon appearing on several consecutive evenings near sunset, rising at roughly the same time each night and leaving only a short period of darkness, was once considered a special provision of nature to allow farmers to continue working into the night without interruption.