Weather is a huge factor but very rarely would cause you to bench a stud. I remember a few games a few years ago that this actually happened. A couple of games in blizzard like conditions.
Another thing is its not only bad weather. A lot of teams historically have problems going to AZ early in the season and playing in the heat.
And weather is not always detrimental. If its a heavy downpour game, RB's usually get more carries and can put up more numbers than normal due to the lacking of the passins game conditions.