Next Blue Moon: Dates & Full Calendar Through 2032
On May 31, 2026, a seasonal Blue Moon will occur. To track it in the sky, use the Sky Tonight astronomy app. Keep reading to figure out the meaning of a Blue Moon!
Contents
- Blue Moon schedule: upcoming Blue Moons at a glance
- What is a Blue Moon?
- Seasonal Blue Moon
- Calendrical Blue Moon
- Blue Moon: Frequently Asked Questions
- What we learned about the Blue Moon tonight: final thoughts
Blue Moon schedule: upcoming Blue Moons at a glance
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.
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?
Seasonal Blue Moons are relatively rare. We normally have 12 Full Moons in an astronomical year, as a lunar cycle lasts approximately one month. However, its exact duration is 29.5 days, which means it takes 354 days to complete 12 lunar cycles. This falls short of the 365/366 days in a year. So, every 2.5 to 3 years, we experience an “extra” Full Moon in a season.
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.
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 сalendrical 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 2.5 to 3 years. Calendrical Blue Moons may appear slightly more often than seasonal ones, but both are rare.
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 the lunar calendar for your location 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!
What we learned about the Blue Moon tonight: final thoughts
A Blue Moon is a particular name for the third of four Full Moons in an astronomical season or the second Full Moon in a calendar month. It is not a specific astronomical phenomenon but rather the result of a mismatch between the calendar year and the lunar one, just like a Black Moon. For an astronomer, a Blue Moon is not any different from some other Full Moon. Check the upcoming Full Moon dates in Sky Tonight or in the dedicated article.
