We are often asked about making application of our products on snow-covered ground. Applications in the late fall and early winter should have the same types of considerations as they do in other parts of the year.
When considering application timing, water should always be the preeminent issue. Water influences the movement of soil applied inputs, and when water has potential to run (and not infiltrate), then perhaps applications should be delayed. These events are not always easy to predict, so using your best judgment is the way to go.