I have hunted plenty of times in the rain . . . and I don't like it. I hunt for enjoyment and I don't enjoy sitting in the rain. I have seen and have killed deer in the rain, but the blood trail can be washed away quickly if it's coming down good. I never found a drop on the last "rain deer" I shot.
Luckily, she fell with-in 45 yards and I found her with-in a half hour. Except for pre-rut and rut now, I'll pass on the rainy days.