Decided to emulate Matt S. and get some serious winter tech running gear. He went Lululemon but I went North Face. Obviously not known for their running gear but they have a performance line which includes the Animaji jacket pictured below. Nice down for the core and traditional heavy long sleeve running shirt material with thumb holes on the arms. Took it for a spin yesterday when it was 34, sunny and not too windy. Wore it over a thin long sleeve running shirt and had no problems. If the base layer had been thicker it would probably work down into the 20s without anything over it. Could easily a wind breaker on top for the blustery days that are coming. All in all very happy with it in place of the sloppy running hoodys and the like which are my usual fare.