running in the cold

Are you doing something weird with your neck?

That would be my first thought. Disclaimer: I am not a doctor and am not giving medical advice.

Having said that, you might want to get checked out by a chiropractor or a sports-orientated physical therapist, as there is a major artery that supplies blood to the back of the head and if there is something odd going on with the muscles and/or verterbrae at your neck, it could cut down the blood supply (and impinge the nerve supply)... in which case you would definitely feel sensations -- almost like a bad headache at the back of your head.

This would be worse when it is cold, as quite naturally the surface blood vessels constrict to keep heat in and your blood pressure goes up. (I'm not sure which comes first!)

I've noticed that the cold weather has done wonders for my arm carriage. I am carrying my arms higher and closer to my body -- almost like a subconscious effort to help keep me warm :) So another thing to do is to look for a change in your running style brought on because it is cold. This may something relatively obvious, such as hunching your shoulders; it may be an alteration in your arm swing. It may be, like I said at the start, that you are doing something weird and Paula Radcliffe-like with your head and neck -- possibly something that you always do -- but because of cold weather's effect on blood supply, you only notice the effect in cold weather.

You could try doing some dynamic stretches/mobilisations for your neck and shoulders (that includes the upper and mid back area because of where the trapezious goes.

Anyone else got a thought on this?