As the temperature begins to warm and the ground begins to thaw, earthworm casts appear, heralding the return of the robins. For this reason, the March full moon is often known as the Full Worm Moon.
Northern Native American tribes knew this moon as the Full Crow Moon when the cawing of crows signaled the end of winter. They also used Full Crust Moon because the snow cover became crusted from thawing by day and freezing at night.
The Dakota Sioux named it Moon When Eyes Are Sore From Bright Snow. The Full Sap Moon, marking the time of tapping maple trees, is a Colonial American variation. To the settlers, it was also known as the Lenten Moon. It was considered to be the last full moon of winter.
2019 Spring Equinox Full Worm Supermoon
In 2019, our March full Worm Moon occurs right after the start of spring—the vernal equinox arrives at 5:58 p.m. EDT, and the Worm Moon turns full at 9:43 p.m. EDT. That makes this the first full Moon of the new season. This is the closest coincidence of a full Moon with the spring equinox since March 2000—19 years ago (remember the 19-year Metonic Cycle?). And it’s our final Supermoon of 2019, but it’s not our closest. That happened in February 2019.