how often is there a super blue moon

A super blue moon, which is a rare event where a full moon is both a supermoon (closest to Earth in its orbit) and a blue moon (a second full moon in a calendar month or the third of four full moons in a season), generally occurs about once every 10 years on average. However, the time between occurrences can be irregular and vary from as much as 20 years to as short as a few years. Supermoons happen 3 to 4 times a year, but blue moons occur about every 2 to 3 years, making their overlap quite uncommon. The next pair of super blue moons is expected in January and March 2037.