This afternoon it was 58 degrees -- warm enough for shorts but still a little cool for just a T-shirt, although in those times, my arms are a little cold for the first 8 minutes or so.
So I broke out my Sugoi arm warmers, that I bought years ago for the bike commute.
But I usually don't like wearing them, since they remind me of Holly Golightly in Breakfast at Tiffany's.
But today I put them on and made sure that they rode high enough on my arm that the end of the warmer was concealed by the sleeves of the shirt.
I ended up wearing them the entire run. It's amazing what having cool air off of your arms can do to your overall sense of warmth.