I ignore the wind chill numbers because

1) I make my own,
B) It all depends on the direction I'm heading, and
iii) they're designed to guide people (and are tested using people) who are just standing around, doing nothing. I also make my own heat.

5F coming home tonight, and I still have my pit zips open.

EDIT: Looked it up, -8F windchill on tonights commute. I was mainly crosswinds, but a few blocks of headwinds.