Anyone who lives in cold weather climate, please help!!?

ok, I know it's summer, but in a couple of months I'm going to be moving to a place where the average temp in Jan. is -4. It is imperative that I have a durable winter boot, so I am just trying to plan ahead. I know that I want to get Sorel boots, but I need help deciding between the Joan of Arctic, and the Caribou. I do love the look of the Caribou, but am worried that it will not be tall enough. I would like to know what people who have the caribou boot in extemely cold climate have to say about it.