The weather has a minor impact on the game, but it's not significant, mainly because if you really study the impact of weather on the NFL (not just listen to the talking heads about it) it is pretty negligible. Also, until there is a way for you to see a forecast and adjust your gameplan accordingly, I don't want there to be a huge impact on one aspect of the game. Some things you'll notice are ball flight path in windy situations, increase in fumbles and slower running in wet conditions. Basically I've tried to include handicaps that are balanced regardless of your game plan until you have more knowledge about the weather when game planning.