Last Saturday morning I did 3 miles in 38-degree weather (about 33 with the windchill) in the rain. Those are really hard conditions to dress for because one the one hand, it's warm enough to be raining rather than snowing, but on the other hand, cold rain can feel much colder and more miserable than snow. For this run, I wore tights, one light and one heavy long sleeved shirt, gloves, and a fleece headband.
This was borderline too much. If I'd been trying to run faster I would have over heated, but since I was just going out to stretch my legs, it was fine to be a little overdressed. It wasn't too windy or rainy by the time I stepped out the door, so the conditions were actually pretty nice for running. I know that it's too cold for some people, but I think the 20s and 30s make great running weather if you're dressed appropriately.