Remember last year in Week 15 when SD played Cleveland during a horrendous snowstorm? Drew Brees should have been a great play against the Browns, but a lot of guys (smartly) used another player because of the horrid conditions.
Had Brees not thrown a 78 yard TD to Antonio Gates, his final line would have been something like 3/5 passes for 7 yards and 0 TD's. They used LT and Chatman all game after the 1st quarter. Anyone needing big numbers from Brees probably got burned there.
That was a perfect example of how the elements can affect a player's stats. Another one would be the "Fog Bowl" that the Eagles and Bears played quite a few years ago. I think both QB's had 4 INT's in that game.