Rain, or no rain, they will roost in the same spot until they get pushed out of it, or until something makes them change thier routine!
Getting them to gobble with-in an hour after they roost, for us, is pretty easy. We drive the roads where we hunt, there is a road every mile, and we use a coyote howler. Simply stop the truck, get out, and howl a couple of times, and they almost always shock gobble.