Cold is relative. How much colder can it be if you're within an hour of the 49th parallel, anyway? Just stay away from the cold states, and you'll be fine, ie: the Dakotas, Montana, Minnesota, etc.

And for goodness' sake, don't go north-north. It's bloooody chilly up there!
We have our bbq going all year round,so how bad can it be?
You know what's kinda cool, though?
http://www.pgc.nrcan.gc.ca/seismo/recent/wc.50evt.html
http://www.cbc.ca/servlet/Weather?query=Vancouver,BC
Just don't go too far north. You're liable to get eaten by a wolverine or something with big teeth.
