Today it was about 48°, cloudy and windy, and it's probably the coldest I've ever run in shorts. Just experimenting to see how I'd do. I wore a single layer on top, my warmest tech jersey, tucked my fingers into the sleeve pockets and I was fine. My thighs and azz sure were cold when I got home, but it really didn't affect me except when I had to stop for traffic. My hands were actually the coldest part of me, even though I never uncovered them. Couldn't get my act together to get out in time to be back before the noon kickoff, but considering the final score was 56-0, I didn't miss much. 
ETA: I shouldn't say the coldest I've "ever" run in shorts. Back when I was in college, and just a jogger, and "warm clothes" consisted of cotton sweats, my rule was "long sleeves below freezing, long pants below 0F." But that was a very, very long time ago...
Last edited by OakLeaf; 11-02-2013 at 04:06 PM.
Speed comes from what you put behind you. - Judi Ketteler