The worm moon is the first full moon in the month of March. The moon in March has a lot of different nicknames:
- the Worm Moon, because the ground begins to thaw and earthworms reappear, soon followed by the return of robins.
- the Crow Moon, because the cawing of crows signals the end of winter;
- the Crust Moon, because the snow cover becomes crusted from thawing by day and freezing at night;
- the Sap Moon, because March is the time to tap maple trees for their sweet sap which is turned into maple syrup;
- the Lenten Moon, because it happens right around the Christian season of lent.
The farmer's almanac included nicknames for the full moon depending on what month they occured. Most of these nicknames were based on the names North American aboriginal people used. Although many tribes gave nicknames to the full moon, the most well known come from the Algonquin tribes who lived in the area of New England and westward to Lake Superior.