In May 2026, a rare and highly noticeable calendar event will occur: the month will contain two Full Moons. For an ordinary observer, this appears as an unusual lunar month, while for astronomical calendars it is an important moment.
Why there are two Full Moons in May 2026
Normally, there are 12 Full Moons in a year; however, in 2026 there will be 13, with May hosting two of them. The reason is simple: the lunar cycle lasts about 29.5 days, while the calendar month of May has 31 days. Occasionally, roughly once every 2.5–3 years, two Full Moons fit into a single calendar month. This rare phenomenon is called a Blue Moon, based on the English expression “Once in a Blue Moon,” meaning something that happens extremely rarely. This event is predictable but infrequent: in 2026 it will be the only one of the year.
The first Full Moon (the Flower Moon) will occur on May 1, and the second (the Blue Moon) on May 31. This means May will begin with a Full Moon and end with one as well, creating the effect of a double Full Moon within a single calendar month.
First Full Moon of May 2026: Flower Moon
The first Full Moon in May 2026 will occur on May 1 at 20:23, during the 14th lunar day. At that moment, the Moon will shine in the constellation Scorpio. The May Full Moon is traditionally called the Flower Moon, a name connected to the period of active blooming in May, when spring reaches its peak. In Chinese tradition, it was called the Dragon Moon, while among the Celts it was known as the Bright Moon.
The May 1 Full Moon is a micromoon — it occurs near apogee, the point in the Moon’s orbit farthest from Earth. Because of this, the lunar disk appears about 5% smaller and 10% dimmer than average. The difference is barely noticeable to the naked eye but becomes more evident when comparing photographs with a supermoon.
Blue Moon: the second Full Moon of the month
The second Full Moon of the last spring month will occur on May 31 at 11:47, on the 15th lunar day of the lunar calendar. The celestial body will be in the zodiac sign Sagittarius. It carries the status of a Blue Moon — the second Full Moon within a single calendar month. The second May Full Moon will also be a micromoon and even farther from Earth than the first, making it the smallest Full Moon of 2026. Despite its modest visual characteristics, the rarity of this event makes it special — Blue Moons occur only seven times every 19 years.
A Blue Moon does not mean that the Moon’s disk turns blue. The name is not related to color but to the rarity of the calendar event. A truly bluish tint is only possible under rare atmospheric conditions, such as smoke or particles in the air, but this is a separate phenomenon and not directly related to the definition itself.
Read also: lunar haircut calendar for May 2026
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