I see plenty of deer in light to moderate rain. I've shot a few in this situation. I'm the guy that will sit in the rain for hours on end, it really doesn't bother me a bit. Now that I have have rain specific gear as well, I'll sit out all day.

I have 2x specific stands of young hemlock on my property that are all 5-10" in diameter and super super thick. The deer flock to these areas and bed down nearly every time it has started raining while I was on stand there. I plan for that now.