I grew up and went to college in Fairbanks, Alaska. My outside running cut-off point was -30 deg F, which meant that there were about 2 weeks a year that I had to run inside (which was mostly running on the walkways above the stands at the indoor hockey arenas).<br><br>
There's some good info here - <a href="http://www.runningclubnorth.org/lcld_prs.htm" target="_blank">http://www.runningclubnorth.org/lcld_prs.htm</a><br><br>
Most of what I would offer is probably old news. A good base layer to wick moisture away from your body. A good, breathable outer layer to stop wind but not sweat. I liked hoodie sweaters as a middle layer because the hood protected my neck, even though they were typically cotton. A good pair of mittens (keeping the fingers together keeps them warm), along with a thin pair of liner finger gloves in case you have to pull the mittens off. I would ball my hands into a fist inside the mittens when I ran. I used a wool scarf around my mouth and nose and developed a technique of directing my breath up to warm my exposed face. The downside there is that you develop a lot of hoar frost and your eyelashes tend to freeze together (you can dethaw them between your fingers easily). Something to keep the boys warm, be it fancy wind-underwear or an old gaiter stuffed down the front of your pants.<br><br>
When I ran this cold, I actually warmed up pretty quickly. The big concern was always that if you stopped, you cooled off quickly and that can be deadly. Try to run where you have escape routes (a store you can step into). Know how you're going to get in touch with someone to pick you up if you twist an ankle. Run with someone if possible. Keep an eye on each other, especially at the extremes like the nose and ears. Frostbite is not fun. Lots of times body parts will go numb with the cold and you won't realize that you've got frostbite. If you do go numb, warming up will hurt like hell.<br><br>
With the right prep, you can run in almost any temp. Attitude (and a good sense of when to play it safe) are a big part of it. And, as always, this is supposed to be fun. If you're miserable in the cold, use the dreadmill or find an indoor track.<br><br>
Mike