A full Blue Moon is coming this weekend — and despite the name, it has nothing to do with color. Early on Sunday, May 31, the moon will become full for the second time in a single calendar month, creating what’s commonly known as a monthly Blue Moon. It’s a simple quirk of timing, caused by the mismatch between the moon’s 29.5-day cycle and our calendar months. Here’s everything you need to know about the Blue Moon 2026.
A second full moon in a single calendar month will occur on May 31 and be best seen at moonrise on May 30. (AP Photo/Michael Probst)
Copyright 2026 The Associated Press. All rights reserved
A rare Blue Moon is coming — the second full moon in a single calendar month, caused by the mismatch between the moon’s 29.5-day cycle and our calendar.
It will occur on Sunday, May 31 — though it will be best seen at moonrise on Saturday, May 30, when it rises in the east during dusk.
On Saturday, May 30, it appears on the eastern horizon at sunset, glowing orange — thanks to how Earth’s atmosphere scatters light — not blue.
The next monthly Blue Moon, like this one, will take place on Dec. 31, 2028. However, there’s a seasonal Blue Moon on May 20, 2027.
A full moon occurs every 29.5 days, but all months except February are slightly longer. That means occasionally, a full moon falls at the very beginning of a month, leaving just enough time for a second one to occur before the month ends. That’s exactly what’s happening in May 2026; the full Flower Moon rose on May 1. So 29.5 days, another full moon rises — and has no name. Hence, it’s called a Blue Moon. However, this is a monthly Blue Moon. Astronomers use another definition: a Blue Moon is the third full moon in a row that occurs within a single astronomical season. That’s called a seasonal Blue Moon, which next occurs on May 20, 2027.
Despite its name, a Blue Moon usually appears orange when it rises; the phrase does not refer to its color. Like the setting sun, a rising moon shines through a thick layer of Earth’s atmosphere. Shorter blue wavelengths scatter easily off air molecules, while longer red and orange wavelengths pass through more directly. This effect, known as Rayleigh scattering, gives moonrises and sunsets their warm, glowing colors.
The best time to see the full Blue Moon will be during dusk on Saturday, May 30. Find an unobstructed southeastern horizon at the time of moonrise where you are, and after a short time, you’ll see a large, orange full moon appear. The naked eye is fine — but you’ll get an exquisite view through any pair of binoculars.
The times and dates given apply to mid-northern latitudes. For the most accurate location-specific information, consult online planetariums like Stellarium.
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