Why it's called the Cold Moon
December's full moon is the Cold Moon — the plainest name in the calendar, for the month the cold settles in to stay. Its beautiful alternative, the Long Night Moon, describes the same fact from the sky's side: it shines through the longest nights of the year.
The Cold Moon in the sky
The Cold Moon is the Wolf Moon's twin: riding at or near the year's highest arc, above the solstice's lowest sun, it stays up longer than any other full moon — up to 15–16 hours of moonlight at northern latitudes.
What the Cold Moon means
Closing the year, the Cold Moon carries completion and rest. In moon practice it's the reflection moon: the cycle's honest ending, reviewed by the year's longest light, before the Wolf Moon opens the next.