I've figured out how to cover the landscape in light and heavy snow and anything in between, but I have not yet figured out how buildings will catch snow on the roof.
OnkelSam, perhaps you know? A dedicated "winter tutorial" coming up?
Digging some more than last night, I found it under Scenario > Atmosphere Properties > Weather.
It's not the most intuitive way to do, so the quickest way is to import settings from a preset. Un-check everything except weather, and from there adjust to your liking.
Making ice is easier than I thought.
Make a body of water, open Scenario > Terrain Properties. At the bottom, under Ice, check the box next to Map uses ice.
Set up the tiling scale to 2 for all textures to get you started.
The tint should have an icy colored look as well.
Now you can paint the ice effects in on your water bodies. Use less strength to gain control over where the ice is cracked and worn, melting or refreezing.
To get the best out of the ice effect you should play around with the sun position and direction in order to get the specular highlights and reflection hitting the ice surface.
There's so many attributes not covered anywhere, so a thorough guide would be very appreciated
Currently playing around with a 2-4p map with height map generated from World Machine where I'll have snow covering the higher altitudes. Think it can be an interesting twist!