Super blue moons are rare: they happen on average about once every ten years, but the exact gap can be anything from a few years up to around 20 years in unusual cases.

What is a “super blue moon”?

  • A blue moon is when there are two full moons in a single calendar month (or, in another definition, an extra full moon in a season). This happens roughly every 2–3 years.
  • A supermoon is a full moon that occurs when the Moon is near its closest point to Earth in its orbit, making it appear slightly bigger and brighter; this happens several times a year, about 25% of full moons.
  • A super blue moon is when both things line up at once: the full moon is a supermoon and also a blue moon.

How often are super blue moons?

  • Blue moons alone: about once every 2–3 years on average.
  • Supermoons alone: three to four times a year, or roughly a quarter of all full moons.
  • Super blue moons (the overlap of the two): on average about once per decade, but not on a fixed schedule.
  • The interval can stretch to around 20 years between events, or sometimes you can get a pair in close succession (for example, a pair predicted in January and March 2037).

Why the timing is irregular

  • The Moon’s orbit and the calendar don’t sync neatly: the lunar cycle is about 29.5 days, while our months and years are based on Earth’s motion around the Sun.
  • Because of this mismatch, the pattern of which full moons are “blue” and which are “super” drifts over time, so super blue moons do not repeat on a simple, fixed interval like an eclipse cycle.

Simple takeaway

  • If you see a super blue moon, you’re looking at a roughly “once-in-a-decade” sky show, with the caveat that the gap to the next one might be just a few years—or closer to 20 years in rare cases.

Information gathered from public forums or data available on the internet and portrayed here.