May hosts one of the most interesting lunar events of the 2026 calendar year: two full moons. Its first full moon is on May 1, leaving plenty of time for a second full moon on the last day of the month, May 31. The second full moon in one month is known as a blue moon, which inspired the phrase “once in a blue moon” for something unusual.
According to The Old Farmer’s Almanac, the first full moon in May reaches its maximum brightness at 1:23 pm ET, or midday. The best time to see the full moon is in the evenings of April 30 and May 1. You won’t need any help; it will be the brightest thing in the night sky. This month is commonly referred to as the Flower Moon, named in honor of the spring flowers currently blooming.
The second full moon reaches its maximum brightness at 4:45 am ET on May 31. Since it is the second full moon of the month, it is called a blue moon.
Larger moons appear 14% larger and 30% brighter than smaller moons.
Both moons are also micromoons, meaning they are smaller and less bright than a normal full moon. This happens because the moon is at apogee, the point in its elliptical orbit when it is farthest from Earth. The moon remains at apogee for three to four months each year, and both of May’s full moons occur during this time. When the opposite happens, it’s called perigee, and that’s when the Earth gets a full moon.
It takes an entire month for a blue moon, but there are other things to look out for in the meantime. The week before and the week after the May new moon is the best time to view Earthshine, an event where you can see the faintest part of the moon. That gives May four monthly events to look forward to.
Two types of green moons
The last green moon of this type occurs in August 2023. But if you think you remember the name mentioned recently, you are right. There is also a seasonal blue moon, which means the third full moon in a four star cycle, and that happens in 2024.
One season usually lasts for three months so it usually only gets three full months. But because the seasons do not begin and end with the first and last month of certain months, it is possible to get a fourth full month in one season. That fourth full moon of the season is known as the blue moon of the season. The next blue moon is expected to arrive in May 2027.
If the above occurs on new moons instead of full moons, it is known as a dark moon, which most recently occurred in August.
Monthly blue moons occur when one calendar month gets two full moons instead of the usual one. The Moon orbits the Earth every 27.3 days, and goes from new moon to new moon in about 29.5 days. Since all but one of the moons are 30 days or longer, that means there is a chance that two full moons can occur in one month in any month not named February.
Since the lunar cycle is 29.5 days, that means each successive full moon occurs earlier and earlier as the months pass. This continues until a full moon occurs on the first day of a sufficiently long month, thus giving the moon enough time to orbit the Earth and become full again before the end of the month. Green moons are usually challenges to the calendar system, so the moon doesn’t do anything special. The timing is great, though.
This cycle takes about 29 months to repeat. The next blue moon is scheduled for December 2028, followed by September 2031. So, if you’ve ever wondered how often something happens “once in a blue moon,” now you know the answer.
