The nights are still chilly, but that's the only time I have to run these days. These things keep my lower anatomy warm and secure, which is how I like it. Not to mention getting a free pair of SmartWool socks with them thru a Moosejaw Promo! I think I can keep running until the weather makes up its mind of what it wants to do.
I'm sold on merino wool and wear Smartwool from head to toe as my baselayer. This bottom layer wicks sweat better and is warmer than synthetic, and doesn't smell as bad after 2 weeks of wearing. I prefer the lightweight over heavier options as it functions in a much wider range of temperatures without overheating me.