At 0.6mi, I turned around and went back to the car to get a cap because my ears were freezing. So then I ran on across the river and back, so I could "re-start" at about 2.4mi. I felt pretty comfortable the whole way except for running back up "the mountain" in mile 9. That's always tough.
The sun stayed out most of the run, so I was comfortable (but sweaty) with my cap, mittens, pants, and two long sleeve shirts on.