The full moon that typically occurs in March is widely known as the Worm Moon, a name connecting the celestial event to the terrestrial changes of early spring. Full moon names stem from a long historical tradition, primarily from Native American, Colonial American, and European sources, which tracked the seasons through lunar cycles. These names served as an annual calendar, marking nature’s progression and helping communities anticipate seasonal shifts. The Worm Moon signals a period of transition, marking the final full moon of winter or the first full moon of spring.
When the Worm Moon Appears
The Worm Moon is the full moon that falls in March, though its timing relative to the beginning of spring can vary. Since the lunar cycle is approximately 29.5 days long, the full moon phase shifts slightly each year. Because of this shift, the Worm Moon can occasionally occur in early April, but it is generally associated with March.
The March full moon is significant because of its proximity to the Vernal Equinox, which marks the astronomical start of spring in the Northern Hemisphere. This equinox typically falls around March 20th. The Worm Moon, occurring just before or just after the equinox, is a reliable indicator that the cold season is ending and the growing season is about to begin.
The Etymology of the Name
The name “Worm Moon” reflects the first signs of life returning to the landscape after winter. The most common explanation ties the name to the emergence of earthworms, which become active as the ground thaws. These earthworms create trails and casts of soil on the newly unfrozen surface, a visible sign that the soil is warming up.
This biological activity draws robins and other birds back north, providing a reliable food source after the scarcity of winter. The name is often attributed to the Algonquin tribes of the northeastern United States, who used these natural cues for their calendar.
However, some historical research suggests an alternative biological origin. Writings from the 1760s propose that the “worms” originally referred to beetle larvae, grubs, or other overwintering insect larvae. These larvae emerge from the thawing bark of trees and winter hideouts, signaling a similar transition from dormancy to activity. Regardless of the specific creature, the name’s meaning remains consistent: it denotes the return of life and the softening of the earth.
Other Names for the March Full Moon
Because different cultures observed different seasonal markers, the March full moon has accumulated a variety of other names. Many Indigenous North American tribes used the name Crow Moon, marking the time when crows returned north from their winter migration. The return of these birds signaled spring’s arrival and the availability of new food sources.
Other names focused on early agricultural and foraging activities. The Sap Moon or Sugar Moon was used by tribes, particularly the Ojibwe, to signify when maple tree sap begins to flow. This period was crucial for collecting sap to make maple syrup and sugar after the long winter. European settlers contributed names like the Lenten Moon, referring to the Christian season of Lent. The term Crust Moon was also used to describe the crust of snow that forms when it thaws during the day and refreezes into a hard surface at night.