But it is rare!
Tonight will be the second full moon in the month, which is why it's dubbed a blue moon. There are usually 12 full moons a year, but in 2015 there will be 13.
Now, the moon can appear blue, but that usually takes a cataclysmic volcanic explosion that sends tons of ash and smoke into the sky creating a filter that makes the moon look blue.
Don't be disappointed, though. A summer night with a full moon is always nice.
We know you're excited, so here's Ella Fitzgerald singing Blue Moon to help you pass the time until the sun goes down and the moon comes up.