The wind chill option suddenly seemed much more bearable.
One of my companions' water tube was frozen solid as it was minus 10 with the wind chill factor.
The summit ascent will normally be undertaken in near freezing temperatures (Even colder with wind chill ).
Above 91° F, wind movement has no effect on the apparent temperature, so wind chill is the same as the outside temperature.
A lightweight, water repellent jacket, which is fully windproof, will allow for improved breathability whilst preventing the effects of wind chill.