when is the blue moon

The next Blue Moon will occur on May 31, 2026. This will be a calendrical (monthly) Blue Moon, meaning it is the second Full Moon to occur in a single calendar month. The next seasonal Blue Moon, which is the third Full Moon in an astronomical season with four Full Moons, will take place on May 20, 2027. Blue Moons generally happen about every 2.5 to 3 years, with the exact date depending on time zones.