Brr, it is really cold here! My personal threshold for running outdoors in the winter chill is about 15 degrees Fahrenheit. I looked around the world wide interwebs for guidance on what I should be wearing to stay toasty. I found a pretty detailed explanation at Runner's World.
Here is the chart, straight from the article (which has other great tips).
30 degrees: 2 tops, 1 bottom. Long-sleeve base layer and a vest keep your core warm. Tights (or shorts, for polar bears).
10 to 20 degrees: 2 tops, 2 bottoms. A jacket over your base layer, and wind pants over the tights.
0 to 10 degrees: 3 tops, 2 bottoms. Two tops (fleece for the cold-prone) and a jacket. Windbrief for the fellas.
Minus 10 to 0 degrees: 3 tops, 2 bottoms, extra pair of mittens, 1 scarf wrapped around mouth or a balaclava.
Minus 20 degrees: 3 tops, 3 bottoms, 2 extra pairs of mittens, 1 balaclava, sunglasses. Or, stay inside.
According to the chart, I dress for no less than minus 10-0 degrees when it is 30 degrees out! Well, I do stop short of wrapping a scarf around my mouth. I find 3 tops and two bottoms (running tights and a second workout pants) to be my comfort zone. I wear mittens that I can peel back and bare my fingers after I warm up, but I always keep my ears covered.
Other note worthy tips for cold weather running included, changing out of running gear as soon as possible when you finish and to warm up indoors prerun.
I have a basic training plan in mind but I can't seem to stop searching and reading other plans. A neat plan that I found uses the Runners World website again. Their smart coach training plan is free and pretty easy to customize. It uses your goal and a past race time to calculate average paces for your training runs and helps guide you to a specific finish time for your upcoming race. This plan really made me realize how I need to actually race when I run a race rather than coast by at my usual training pace. What I really liked about this tool is that you can select your long run day and the tool adjusts your training week from there.
My last cool find is a treadmill pace conversion chart! Like I said above, I have no shame in hitting up the treadmill for temps below 15 degrees. Personally, running on a treadmill doesn't inspire me to up the ante and use the incline feature. In my mind, I am a winner for not just going back to bed so it is not likely that I am going to challenge myself too much on the treadmill. This chart is a great motivator for me to either push my pace or try to increase the incline for at least part of my treadmill runs.