Snow is an add-on for Blender that adds snow to selected objects in your scene. It works with a single click, and you can adjust snow height, direction, shape and detail as needed. Because it is geometry based rather than texture based, the developer notes it handles a reasonable level of object complexity, and suggests using ground geometry rather than every object when covering something like a grass field.
Controls include a Simple Snow option for fast feedback or lower poly counts, adjustable resolution for detail, bulge, and noise controls. A slope threshold limits snow accumulation based on slope steepness, and a sheltered areas setting keeps snow off from underneath objects. You can also create footprints or other prints using any object or collection in the scene.
Snow can be activated by pressing F7, or selected in Object Mode under the Object/Snow menu. A demo video is available. The add-on comes in two variants, Snow and the essential Snow_ES, with documentation provided.