Top line
A full Blue Moon is coming this weekend, and despite the name, it has nothing to do with the color. Early on Sunday, May 31, the moon will become full for the second time in a single calendar month, creating what is commonly known as the monthly Blue Moon. It is a simple coincidence of time, caused by the mismatch between the 29.5-day cycle of the moon and the months of our calendar. Here you will find 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 will be best seen when the moon rises on May 30. (AP Photo/Michael Probst)
Copyright 2026 The Associated Press. All rights reserved
Key facts
A rare Blue Moon is approaching: 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 happen on Sunday, May 31, although it will be best seen when the moon rises 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 occur on December 31, 2028. However, there is a seasonal Blue Moon on May 20, 2027.
What really is a ‘blue moon’
There is a full moon every 29.5 days, but all months except February are slightly longer. That means that occasionally, a full moon falls at the beginning of a month, leaving enough time for a second one to occur before the month ends. That’s exactly what will happen in May 2026; The full Flower Moon rose on May 1st. Then, 29.5 days, another full moon rises, and it has no name. Hence it is called Blue Moon. However, this is a monthly Blue Moon. Astronomers use another definition: a Blue Moon is the third consecutive full moon that occurs within a single astronomical season. This is called a seasonal Blue Moon and will occur on May 20, 2027.
Why a ‘blue moon’ is not blue
Despite its name, a Blue Moon usually appears orange when it rises; the phrase does not refer to its color. Like the setting sun, the crescent moon shines through a thick layer of Earth’s atmosphere. Shorter blue wavelengths scatter easily from air molecules, while longer red and orange wavelengths pass through them more directly. This effect, known as Rayleigh scattering, gives moonrises and sunsets their warm, bright colors.
When to see the ‘blue moon’ rise
The best time to see the full Blue Moon will be during dusk on Saturday, May 30. Look for an unobstructed southeastern horizon at the time of moonrise where you are, and after a short time you will see a large orange full moon appear. The naked eye is fine, but you’ll get an exquisite view through any pair of binoculars.
Times and dates indicated apply to mid-northern latitudes. For the most accurate information on the specific location, check out online planetariums like stellarium.