This could be a reason in singleplayer for doing a level with no aircraft where they would make the level easier.
You could have those types of effects in SP alone and tweak it for MP so that players need to ramp up and obtain a Frostbite resistance Buff or add it in as an obtainable Generals Power for people to select. Another idea is to simply upgrade the Barracks so the infantry alone wear better weather resistant clothing across the board.