Next Blue Moon 2026: Date, Time, and Full Calendar
The next Blue Moon in GMT/UTC will occur on May 31, 2026. In this article, you’ll learn what a Blue Moon is, see upcoming Blue Moon dates, and find out how to spot them in the sky with the Sky Tonight astronomy app.
Contents
- Next Blue Moon Dates: Full Calendar Through 2032
- What is a Blue Moon?
- Seasonal Blue Moon
- Calendrical Blue Moon
- Blue Moon: Frequently Asked Questions
- Blue Moon: Key takeaways
Next Blue Moon Dates: Full Calendar Through 2032
Curious when the next Blue Moon will rise? This quick-reference calendar highlights the upcoming Blue Moons through 2032. Mark your calendars!
- Calendrical Blue Moon: May 31, 2026, 08:45 GMT
- Seasonal Blue Moon: May 20, 2027, 10:59 GMT
- Calendrical Blue Moon: December 31, 2028, 16:48 GMT
- Seasonal Blue Moon: August 24, 2029, 01:51 GMT
- Calendrical Blue Moon: September 30, 2031, 18:58 GMT
- Seasonal Blue Moon: August 21, 2032, 01:46 GMT
Let’s explore the two types of Blue Moons – seasonal and calendrical – and uncover why people began keeping track of them.
When is the Blue Moon in 2026?
The Blue Moon will occur on May 31, 2026, at 08:45 GMT. It will be a calendrical Blue Moon, which means it is the second Full Moon in a calendar month. Depending on your time zone, the Full Moon may fall on a different local date, which can affect whether it is counted as a Blue Moon where you live.
What is a Blue Moon?
The origin of the name is still unclear. It has been around for a long time; some even trace it back to 400 years ago, when it meant something that could never happen (hence the English expression “once in a Blue Moon”).
A Blue Moon can be seasonal and calendrical. Let’s take a more detailed look at each definition.
Seasonal Blue Moon
A seasonal Blue Moon is the third Full Moon in an astronomical season with four Full Moons. As a rule, each season (defined by solstices and equinoxes) has three months and three Full Moons, but sometimes it has the fourth Full Moon.
How often does a seasonal Blue Moon occur?
A seasonal Blue Moon occurs roughly every 2 to 3 years. The reason is that a Full Moon occurs about every 29.5 days, so 12 lunar cycles last only about 354 days — around 11 days fewer than a solar year. Because of this mismatch, an extra Full Moon occasionally appears, and sometimes a season ends up with four Full Moons instead of the usual three. In that case, the third Full Moon is called a seasonal Blue Moon.
When is the next seasonal Blue Moon?
- May 20, 2027, 10:59 GMT
- August 24, 2029, 01:51 GMT
- August 21, 2032, 01:46 GMT
Origins of a seasonal Blue Moon
The curious thing about a seasonal Blue Moon is that it’s always the third Full Moon in an astronomical season of four Full Moons. But why not the fourth?
The possible explanation refers to the Christian ecclesiastical calendar. In calculating the dates for Lent and Easter, Catholic clergy identified the Lenten Moon (the final Full Moon of winter) and Easter Moon (the first Full Moon of spring). The third Full Moon of the season arrived too early and upset the arrangement of Church holidays. It was marked a “betrayal Moon” to ensure that Lent and Easter corresponded with the right Full Moons and that other festivals would still fall on their “proper” dates.
According to the other version, the tradition dates back to the 19th century. The now-defunct Maine Farmer’s Almanac calculated and listed all of the Full Moons in a year, along with their traditional names that had to correspond with the particular months. So the authors had to use a special name for the “extra” Moon to make things work.
If you want to learn more about the traditional names given to the Full Moon by the Native Americans and other peoples, see our colorful Full Moon Calendar 2026.
Calendrical Blue Moon
The lunar cycle is about 29.5 days. Most calendar months are slightly longer, with 30 or 31 days. This means there's often a narrow window where two Full Moons can fit into a single month. For example, if a Full Moon happens on the first or second day of the month, there’s just enough time for the next Full Moon to arrive at the end of that same month. When that happens, the second one is known as a calendrical Blue Moon.
How often does a calendrical Blue Moon occur?
Calendrical Blue Moons may occur more often than seasonal ones. However, they are not the same worldwide, as the exact Full Moon dates depend on the time zones. For example, China, Japan, Korea, Australia, New Zealand, and many other countries (observing the time zones that are at least 8 hours ahead of Greenwich) will experience a calendrical Blue Moon on January 30 and then on March 30, 2029, while the rest of the world will only see one calendrical Blue Moon on December 31, 2028.
When is the next calendrical Blue Moon?
- May 31, 2026, 08:45 GMT
- December 31, 2028, 16:48 GMT
- September 30, 2031, 18:58 GMT
Note that the exact date of a Full Moon may differ depending on your time zone. Use the Moon tab in the Sky Tonight calendar to see which month has two Full Moons according to your local time.
Origins of a calendrical Blue Moon
The majority of us are familiar with the calendrical Blue Moon. This is the most widely recognized and well-known definition. However, it is a result of a mistake made by amateur astronomer James Hugh Pruett. Back in 1946, he misinterpreted the seasonal definition while writing an article for Sky & Telescope magazine. The wrong definition has gone viral in the media and has become even more popular than the original one.
Blue Moon: Frequently Asked Questions
When is the next Blue Moon?
The next Blue Moon will occur on May 31, 2026, at 08:45 GMT; it will be a calendrical Blue Moon. The next seasonal Blue Moon will take place only on May 20, 2027, at 10:59 GMT.
How often do Blue Moons occur?
Blue Moons occur about once every 2 to 3 years. Calendrical Blue Moons may appear slightly more often than seasonal ones, but both are rare.
What is the difference between a seasonal and a calendrical Blue Moon?
A seasonal Blue Moon is the third Full Moon in an astronomical season that has four Full Moons. A calendrical Blue Moon is the second Full Moon in a single calendar month. In other words, the difference is based on how the extra Full Moon is counted: by astronomical season or by calendar month.
How many Blue Moons are there in a year?
As a rule, we have no more than one Blue Moon in a year. However, as the Blue Moon dates can shift slightly according to the time zones, some regions may experience two calendrical Blue Moons in a year. Try checking our Moon Phases Calendar to see if you can have two Blue Moons in one year.
Is a Blue Moon actually blue?
Although it is called “blue,” and many pictures show the Moon in bluish tones, the actual Moon has nothing to do with this color. In the sky, it looks pale gray or white.
Sometimes, the Moon can look blue, but this phenomenon cannot be predicted and mainly depends on atmospheric conditions. For instance, in 1883, after the volcano Krakatoa erupted, the Moon appeared bluish due to the dust in the air.
The lunar surface actually features patches of gray, light blue, brown, and yellow. Can you tell why it appears red, orange, or white when observed from the Earth? Pass our quiz about the colors of the Moon and check yourself!
Blue Moon: Key takeaways
A Blue Moon is the name given to an “extra” Full Moon — either the third of four Full Moons in an astronomical season or the second Full Moon in a calendar month. It is not a special astronomical event but the result of how the lunar cycle fits into our calendar system, similar to a Black Moon. For astronomers, a Blue Moon is no different than any other Full Moon. To keep track of upcoming Full Moon dates, use the Sky Tonight astronomy app or check the Full Moon calendar for 2026.
