Thanks! I chose my M6 this particular day because I figured its a mechanical camera and it won't matter too much if it gets a bit wet (unlike a camera with AE like an M7 or ZI). And get wet it did. I didn't do anything special to protect the camera while shooting except to wipe the snow off the top plate every few minutes. Then when I got on my train I wiped the camera down with a hand towel as best I could. Then once I got to my office I placed it on my desk to dry. The office humidity is very low (30-35%) so the camera and lens completely dried quite quickly and still works perfectly.
You don't have to worry about fungus in cold weather because its too cold for it to grow, but condensation caused by sudden big temperature changes (such as when going from inside to outside with your gear) can be a problem. And that can cause haze. Just have to dry out the camera and lens properly after use