Can I insulate windows using snow?

Theoretically, in the right part of the world you could use snow to insulate windows. Snow is used to build igloos and provides a sturdy wind-proof and well-insulated shelter when used in this capacity.

It may seem ironic to think of using snow as a protection against cold, but it is entirely possible if there is an adequate snowfall in your area and assuming the windows are located close enough to the ground level to make it feasible. Using a shovel to pack the snow against the side of the house and cover the windows would effectively insulate the windows.