Fahrenheit Freak here so really am not too sure of the conversions. (too lazy to look) But I know you question referenced above freezing temps. I agree with the others. Above freezing you don't need a lot of consideration.

If you pedal hard you have the greatest heater known to man, your own body. When temps dip only a few degrees below freezing the game starts to change. I have been amazed so far, how much heat one can generate on a bike. It is VERY hard to get cold at freezing temps unless you are putting out very little effort.