CHICAGO (CBS) — After a clear and cold night Friday night, Chicago is in for a rare treat on a mild and windy Halloween on Saturday, as a blue moon will light up the night sky.

Temperatures will drop to near the freezing mark on Friday night, and then southerly winds will increase throughout the day on Saturday, especially into the evening as a cold front gets closer. It will be sunny and mild during the day, with a high around 57.

(Credit: CBS)

Saturday night brings the second full moon of October, also known as a blue moon.

According to Farmers Almanac, while the moon won’t appear blue in color, the uncommon occurrence of a full moon on Halloween happens roughly once every 19 years and it’s a pattern known as the “Metonic Cycle.”

The 19-year pattern means that 2020 will be the last time we see a full moon on Halloween until 2039 and according to astronomers, a Halloween full moon will occur in 2058, 2077, and 2096.

This is the first time since 1944 that everyone, in all time zones, will have a full moon in the sky on Halloween — meaning every person around the world will experience the Halloween blue moon together for the first time since World War II.

This moon is also known as the Hunter’s moon, which is the first moon following the harvest moon. It was likely named for the time of year to go hunting in preparation for winter. Other names include the Blood moon, Sanguine moon, Travel moon and Dying Grass moon.

(Credit: CBS)

Here at home in Chicago, as the blue moon lights up the sky, temperatures will drop quickly early Sunday behind a cold front, as winds become northwest, falling to near freezing again.

Temperatures will struggle Sunday, with highs in the upper 30s.

Thankfully, there’s lots of sun next week, with a warming trend, as highs will reach the upper 40s on Monday, the upper 50s on Tuesday, and the mid 60s the rest of the week.

(Credit: CBS)