By Brian Lada AccuWeather meteorologist and staff author
May 16, 2019, 8:17:25 EDT
An unusual full moon fills the sky on Sunday evening – a type of moon that will not rise up to 2021. Many people know the term "blue moon" and know it as the second full moon in a calendar month. However, there is another way for a full moon to serve this well-known nickname.
An American Airlines passenger plane from Miami crosses a blue moon over Whittier, California, which it leads to Los Angeles airport, Friday July 31, 2015. (AP Photo / Nick Out)
] " A season-winter, spring, fall, summer-usually has three full moons.If a season has four full moons, then the third full moon in the season can be called a Blue Moon, "the old farmer's almanac explained on his site.
This weekend's full moon becomes the third of four in the spring, making it a blue moon. The first full moon in the spring fell on March 20, 2019 at 9.43. EDT, less than four hours after official spring start.
Seasonal blue moons are not very rare, which occur once every two or three years. The next seasonal blue moon falls on August 22, 2021.
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Many people across the US who go out on Saturday night may watch out to see a cloudy sky rather than the blue moon.
A strong system in the central United States will spread clouds over most of the region from the Gulf Coast to the Western Great Lakes and west to the Rocky Mountains.
Meanwhile, an out-of-season storm, moving from the Pacific Ocean to spreading clouds over most of the Western United States,
The best viewing conditions may end up being across the eastern US, but clouds and mock showers may still  blue moon forecast may 2019 “/>
The weekend's lunar month can be called some other nicknames in addition to a blue moon.
"The full moon of the month marked a time for increased fertility, with temperatures warm enough to safely carry young, a close end of late frosts and plants in bloom," the old farmer's almanac reported.
For this reason, May is full moon known as Hare Moon, Flower Moon, Milk Moon and The Budding Moon.
Despite their nicknames, Saturday night will look like other full moon throughout the year.
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