Afaik (and it was confirmed by CPT members) the weather effects can't be disabled/enabled via some console command.
Like Negative said, we though some time ago that maybe editing some texture (and making it 100% transparent) would disable the fog, but maybe the weather effects don't use a texture or we didn't found the right one.
One trick would be to change the time in game. Usually that changes the weather also.
Console command: game.SetTime(11,47) for 11:47. Play with other time values until you get rid of the fog.
Or sleep in a bed, that also changes weather.
Last edited by Larisa; 07.01.2009 at 14:56.