Is it too cold to run?
Not if you dress correctly and don’t stay out too long.
On cold days, you'll lose a reported 10% of your heat from your head, so keep it covered. Here's what you'll need for your head and neck:
Neck Gaiter or Bandana
Layering is the key for your mid-section. Your base layer should be made from a synthetic wicking material, such as DryFit, Thinsulate, Thermax, CoolMax, polypropolene, or silk. This will wick the sweat away from your body, keeping you dry and warm. Make sure you don't wear cotton!
Your second layer should be an insulating material, such as fleece. Some fabrics suggested for your second layer: Akwatek, Dryline, Polartec, polyester fleece, Microfleece, Thermafleece and Thermax.
Your third, or outer layer, protects you against wind and moisture (rain, sleet, snow), It's a good idea to wear a jacket with a zipper for this layer, so that you can regulate your temperature by zipping it up and down. Suggested outer layers: ClimaFit, Gore-Tex, Microsuplex, nylon, Supplex, and Windstopper.
You can lose as much as 30% of your body heat through your extremities, so it's important to cover those hands. Wool running gloves or mittens are fine unless it is raining or snowing, then you’ll need a waterproof, or at least water resistant light glove.
Your legs generate a lot of heat so you don't need as many layers on your lower body. You can usually wear just a pair of tights or running pants made of synthetic material such as Thermion, Thinsulate, Thermax, Coolmax, polypropolene, and/or silk.
Never wear cotton socks (in cold or warm weather) when running because they won't wick away the moisture, leaving your feet wet and prone to blisters. Instead, be sure to wear a good pair of wicking socks made of fabrics such as acrylic, CoolMax, or wool.
So, go play in the cold, just dress for "success." Have fun!