Halloween night will be extra spooky this year, as a rare lunar event is set to light up the night sky — and it only happens “once in a blue moon.”

A full moon will appear on Oct. 31, 2020, Farmers’ Almanac said. Such an event occurring on Halloween only happens every 18 to 19 years, so it will be an extra-special spectacle, according to the periodical.

The first full moon, called the “harvest moon,” will appear on Oct. 1.

To add to the rarity of Halloween night, a blue moon only happens every two and a half to three years, according to Farmers’ Almanac. It will reach peak illumination at 10:51 a.m. ET on Halloween morning, but will appear full that night too, the periodical added.

After 2020, we will next see a 100%-illuminated Halloween full moon in the years 2039, 2058, 2077 and 2096, the Farmer’s Almanac said.

The next full moon in 2020 after Halloween will be November’s “full beaver moon.”