As I got older, I just quit hunting in the rain, but back in the day, I would stay out in some pretty bad stuff. In the warm early season, I didn't worry about wet as long as I didn't get chilled. So, any quiet rain clothing was sufficient. Yeah, I never was real bright, so sitting in the rain felt fairly normal. Perseverance is key.
However, the one thing that was crucial was protection of the fletching. Coating the feathers with a water repellant treatment as well as keeping extra arrows covered is good. Still, a certain level of precipitation makes even gung ho deer take cover. Likewise, the wise hunter knows when it is just too stormy to be out.