No, not who is going to win or lose but where it is going to rain. The map below is for the calendar day (central time) of the election and forecasts the amount of rain (scale at left, click to enlarge). The forecast is from the National Weather Service’s GFS model.
It is said that rain favors Republicans. I have no idea whether that is true. If it is true, then the race that might be most affected is Patty Murray’s Senate seat in Washington where heavy rain is forecast.