At a Glance

Watch a livestream of the bluemoon rising on The Weather Channel app from 9-10 p.m. Friday.The next time you'll be able to witness a blue moon is Halloween night 2020.

The second blue moon of 2018 is set for Saturday morning and will be the last one to adornthe night sky until 2020.

Saturday's Sap Full Moon,which is also a blue moon because it is the second full moon of the calendar month, is set to peak at8:37 a.m. EDT.

The first full moon this month occurred on March 2. The next blue moon will occur Oct. 31, 2020.

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A blue moon is not as rare as the expression "once in a blue moon" implies. Although Saturday's blue moon will be the second in 2018 — the first occurred Jan. 31 — they typically , according to space.com.

Saturday's blue moon will be the last until Oct. 31, 2020.

(NASA)

The fourth full moon of the year is given the name for sap that makes all sorts of syrup. It's also sometimes known as the Worm Full Moon because it's the time when earthworms emerge from their winter slumber, according to the Old Farmer's Almanac.

Not everyone will have the benefit of seeing Saturday's blue moon, considering the changing spring weather.

Accordingto weather.com meteorologist Linda Lam, people living in the South, Southwest and West Coast have the best chance of seeing the blue moon. However, she notes that it is still several days away and the forecast details remain uncertain.

Others hoping to catch the last blue moon until 2020 may be disappointed. An area of low pressure may bring clouds, along with snow and rainto much of the Midwest and Great Lakes regionSaturdaymorning. Portions of Montana and Wyoming may also see snow showers and cloud cover.

Depending on how quickly a cold front pushes off the East Coast, clouds may block the view along much of the East Coast,Lam said.

Watch a live stream of the bluemoon rising on The Weather Channel app from 9-9:30p.m. Friday.