By Brian Lada AccuWeather meteorologist and staff writer
May 16, 2019, 8:17:25 AM EDT
An unusual full moon will fill the sky on Sunday night – a kind of moon that will not rise again until 2021.  Many people are familiar with the term & # 39; blue moon & # 39; and knows it as the second full moon in a calendar month. However, there is another way for a month to earn this well-known nickname.
An American Airlines passenger plane from Miami is crossing a blue moon at Whittier, Calif., While it goes to Los Angeles Airport, Friday, July 31, 2015. ( AP Photo / Nick Ut)  "A season-winter, spring, autumn, summer-usually three full months. If a period of four full months, then the third full moon in the period may called Blue Moon, "the Old Farmer's Almanac is explained on its website.
The entire weekend month will be the third of these four springs, making it a blue moon. The first month of spring fell on March 20, 2019 at 9:43 pm. EDT, less than four hours after the official start of spring.
Seasonal blue lunar times are not rare, occurring once a year or three years. The next seasonal blue moon falls on August 22, 2021.
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Many people throughout the United States walking outdoors on Saturday night can find a sky full of cloud instead of the blue moon.
A powerful central US central system will spread clouds throughout the region, from the Gulf Coast to the west of the Great Lakes and west of the Rocky Mountains. Meanwhile, an out-of-season storm moving from the Pacific Ocean spreads clouds in almost every western US
The best viewing conditions may hit the eastern US, but these may still be clouds and spotting rain interfere with looking at parts of mid-Atlantic and Deep South.
This weekend's full moon may be called some other nicknames other than a blue moon.
"The month of May is marked with an hour of increasing fertility, with enough temperature for safe delivery of children, a close end to late frosts, and flowering plants, "the Oldman Farmer almanac reported.
Consequently, the entire month of May is known as the Hare Moon, the Flower Moon, the Milk Moon and the Budding Moon.
Despite its nicknames, the Saturday night of the month will appear like all other months throughout the year.