What part of your anatomy gets cold first... to the point of being uncomfortable?
Ears? Nose? Fingers? Toes? Somethin' else?
My fingers are always the first thing that "stings," if I'm not wearing the full-finger gloves. Maybe it's because I'm using my fingers, and my ears and nose are just up there, hangin' useless on my head.
Below 40F, my fingers get uncomfortable. I'm good down to about freezing, without ear protection. Pretty much everything else can handle the 15-minute commute ride without discomfort, down to single digits or so.