Snow is good, it creates realism other than the weather being the same all the time, but now with the rain it's even better. Snow personally doesn't effect me but I notice that many players complain about the fact it causes them lag.
The snow makes my good PC lag for odd reasons, guess its garry's mod that gets bottle necked. It also looks pretty bad, more like nuclear fallout than anything else.
Also the fog effect is WAY too dense, you can't see 5 meters in front of you. Increase the view distance during the fog, and it might be cool, and change the color from brown to white or grey.
Overall, snow is too frequent, I don't like it, it should be replaced by the rain, that's already in the game, but it just never appears, rain causes a lot less lag, and it looks a lot better than the snow, because it looks like rain, rather than some paper left over from a hole punch being thrown around.
The snow is useless, it doens't add anything to the game. The fog is better actually, the fog really adds something to the game, you really have to watch out how and where you drive/walk. I rather have more fog then snow.
Because of the lag I would like to get the snow deleted. Of course it adds some realism to the game, but we would like to keep some smooth gameplay too..
Then you have the fog: The fog can get reduced indeed, but not deleted. I would like to have the fog to be less rare and at one time a bit foggy and another time heavily foggy.