I think Rain is probably the best thing that can happen after I get to my stand. It washes your scent out from where you walk to your stand.
From coon hunting with dogs, I have found that once it starts to rain, it gets very hard for a dog to pick up a trail, and if it rains hard or for very long, you might as well go home.
By washing out the human scent it seems to make deer move better if there are very many hunters in the area. Most hunters will pack up and go to the house, leaving the die hards like me, sitting in there stands with no trace of human scent in the area.