Air Operations, Battle of the Bulge

[Wayne]

I noticed in the first turn the allies were using their full air complement against the German forces. The issue I have is that the turn was showing rain but both air forces Allied and Axis were available for sorties. Is there a combat modifier for air operations in the rain which counts against their attack value? I would think that if it was raining, both forces would remain on the ground waiting for clear weather.

Thanks,
Wayne