In some maps, such as for example Operation Locker, you get some frost in your field of view. Does it have any effect, besides slightly obscuring the field of view?
The effect on screen is the only one that is created. There are no changes to the accuracy values (for example) of your weapons.
However if you stay in the area for more than a second then I find the effect gets to a point where it's practically impossible to shoot at anything accurately that isn't point blank.
It also seems to be worse in the are just a few feet back from the opening into the building. You can see this very easily in any of the three entrances on Operation Locker DM, but luckily in that case, if your standing there for more than a few seconds, then you will probably be dead!