You know its cold when the water in your drinks bottle freezes. It was -8 when we set off yesterday for 23 hilly miles in Gloucestershire. I purchased a good quality wind stopper and winter coat over Xmas and so far have been out pretty much every weekend this year including a 70 mile Audax. The only slight problem yesterday especially on the hills (one of which is a real climb) was inhaling the cold air. Other than that it was great to be out.