Rain brings everything to life. Greens get greener, rocks glisten, and the darkness of storm clouds makes everything more vivid.
It makes the woods feel more dense, creating a wall of separation between you and the road. Part of that has to do with the lack of light, restricting any sight of buildings you might have gotten in the sunlight, but the rain does its part as well.
The drops that fall on you after bouncing off the tress awaken your skin and makes you aware of your hair and your clothes, which are getting the same treatment as everything else around you. In dry sunlight you are a trespasser, but when water falls on you as it falls on the trees, and the dirt, and the rocks, and into the stream as it does onto you, then you feel like a part of everything around you.
And you belong.