I've spent time in Calgary and Red Deer with the petro business. It gets COLD up there (and Edmonton can be even colder). Worst I saw was around -10 C but it can get much colder. Occasionally in the midlle of winter you'll get a Chinook wind that will warm things up above freezing, then the temps will plunge down again.

Will you be working in the field or indoors? Either way you'll want the warmest stuff you can find. I reccomend buying it in Canada because they'll be selling stuff good enough to protect you, you'll be able to try it on (versus buying on-line) and you won't have to risk losing it to some sticky-fingered baggage handler.

On other note, old field hands up there reccomended I stay away from cheap plasticy materials as when it gets really, really cold these materials turn brittle and break. They prefer leather, ventile or other stuff like that. Expensive, but worth it.

-Blast