I guess I also have learned for experience. If I wake up and its raining - I don't go. (except for turkey - because for some reason they love being out in a light rain) It must keep their dander down and get rid of the bugs that bother them. When I'm archery hunting I seldom still hunt. And in rainy weather I've found that deer don't move too much. But right after a day or two of rain, I try to be out there.
Honestly, I'm out there for the pure enjoyment. If I happen to harvest an animal all the better. But I don't want to get sick or be miserable doing it. Besides, when its wet, I can't hear. My hearing is just about shot.