First, let's discuss blue moon, an extra full moon in a month first.
As the full moon reveals itself between the first two dates of a month, it is likely that a blue moon will appear on one of the last two dates of a month.
Even so, it is also possible blue moon will appear at the beginning of the month after.
By 2018, after this January, the blue moon will happen again on March 31, with the first full moon taking place on March 2nd.
On average, full moon occurs once every month, with an additional full moon appearing about 7 times every 19 years. It can be said, only about 3% of all the phenomena of the full moon is a blue moon.
Previously, the last blue moon appeared on July 31, 2015. While this appearance will happen again, after 2018, on October 31, 2020.