On top, I wore:
-an old Vanderbilt beanie, made of who-knows-what
-a tank top
-a long-sleeved UnderArmor shirt
-a zip-up Mountain Hardwear hoodie
-a Marmot fleece with underarm zippers for venting
-North Face glove liners
On the Bottom, I wore:
-knee-high Smartwool socks
-Salomon running tights, slightly insulated
-an old pair of warm-up pants
None of the layers that came into contact with my skin was cotton, though I think the warm-up pants contained some in the lining. Cotton is a no-no for running in general: In cold weather, it makes you cold when it gets damp, and in any weather it rubs uncomfortably when wet. Synthetics or wool are better choices. Cotton, dear reader, is not your friend.
Usually, one wants to feel pretty cold for the first few minutes of one's run; a chilly start usually means a comfortable internal climate once one's heart gets pumping. I'd opted to do a tempo run for three reasons: 1) I needed to do one at some point anyway; 2) to get myself warmer faster; and 3) to get the workout over with as quickly as possible. The first few blocks, which served as a warm-up, were chilly indeed. I've heard people complain that it hurts to breathe in very cold weather, an effect amplified when one breathes harder due to exertion. This has never been a problem for me, but my chin quickly became numb, my cheeks stung, and my eyes watered. My feet threatened to go numb, too, but within a few minutes they'd warmed right up.
I did the rest of my run quickly, not because I was too cold but because I was too hot and had nowhere to stash discarded layers. I shed my hood, unzipped my top two layers a bit, and barreled toward my apartment, careful to dodge icy patches on my sidewalk all the while. Safely inside, instead of heading for a hot shower I pulled layers off like a woman possessed, stopping only once I'd gotten to my base layer and could feel drafts against my skin. I considered opening a window, but decided against it for Ed's sake.
Were I to live somewhere that regularly gets this cold, I think I'd invest in a light, loose pants layer that has vents so as to be able to regulate my temperature more effectively. My Salomon tights are great, but I think I'd need something light and windproof to go over them. I should probably have left the hat at home in favor of my fleece headband, too; with a hood, I could have kept the top of my head warm as necessary but still been able to vent by pulling it off. Another plus is that a headband is easy to loop around a wrist if it gets too hot, something you can't do with a hat. Also, the knee-length socks were overkill, though my ankle-high Smartwool socks would be a better alternative than the synthetic shorties I wear during warmer months. I'm on the fence about the top fleece layer - I'd make other adjustments before forgoing this, I think.
So Shelly, 14 degrees with windchill is not too cold to go for at least a short run. In 40 minutes I felt just fine, though spending hours outside in that temperature would cause one to burn lots more calories than usual and necessitate carting along some extra fuel. It could also necessitate a face mask. I can't do more than speculate about that for now, but I can say that it's certainly easier to run when it's 14 degrees than it is to walk at that temperature. And you get the running path pretty much to yourself.
Other, miscellaneous tips gleaned from past winters: Bring tissues (or make peace with wiping your nose on your sleeve). Don't stop for too long because it's hard to warm back up again, and if you must stop for a while, zip back up, pronto. You'll be too hot initially, but you'll be glad you did as your body temperature dips. Watch for puddles, and ice patches. And tucking in layers keeps you warmer.