I have had reasonably good luck seeing deer in the rain. I think it helps if the wind is a bit gusty as mentioned. I believe there is no way to truly cover your scent, and the gusty wind seems to confuse deer as to where the scent may be coming from. The woods will be quiet (quiet for you and quiet for them) and you will need to keep your eyes open and scan your shooting zone frequently. They will sneak up on you much easier in the rain and your vision is a bit reduced. Stay alert!
Heavy rain really sucks and deer will often bed down as mentioned.
Without wind or a light breeze, your scent will tend to be more confined to your immediate area. So, read the light wind direction and stay alert!
I wear a camo parka with a cheap walmart orange vest over the outside to stay legal. Make sure it is oversized and fits. Sometimes I tie a tarp between some trees and get under it if you are hunting on the ground and mostly stationary. But you don't want it flapping around making a lot of noise and movement. Even a little protection is often welcomed.
I find if it is breezy and still hunting (stalking) suits you, it is a good time to carefully make your way through the woods very quietly. You have to be even more alert.
If you are hunting state game lands or national forest, there will be lots of hunters and remember they can't see you as easily, so be careful.