Alaska at -40 to -50
Being from South Louisiana I certainly wasn't looking forward to Arctic Weather. However, it's all about having the proper gear.
Spent a couple of week in Northern Alaska (January 2012) where the temps were regularly reaching -40 to -50 degrees for extended periods of time. With my North Face Baltoro 400 III boots, I purchased from backcountry.com, my feet never even thought about getting cold.....nor did they sweat! These boots remained dry the entire time and were so very comfortable!