It happens once in a blue moon, so to speak, and it's happening in June.
Two full moons will rise in June, rather than the usual one per month.The first full moon was Saturday. The moon will be "blue," June 30 at 9:58 p.m.
National Weather Service meteorologist William Alder said the phenomenon happens once every 18 months or so. It happens because the moon's cycle is slightly shorter than most calendar months.
"When you have two full moons in the same month, it's called a blue moon," Alder said. "That's where the expression comes from."