Snow mold is a lawn disease that arises over the winter while grass is blanketed by a cover of snow. It often appears as a web-like patch and is white/grey in color or can have a pink tone. Snow mold most often occurs on healthy lawns with an abundance of nutrients when the grass is left long enough to fold over itself from the weight of the snow. This provides both moisture, shelter, and food for the mold to thrive.
But can it hurt your lawn? If around for extended periods of time, yes it can. However, this usually isn't the case. More often than not, the mold disappears along with the snow. Rising temperatures and air dry out your lawn making it inhabitable for the mold to survive. To prevent seeing it in the spring, make sure to cut your grass short during the fall and remove any debris like leaves that will hold extra moisture.