Mostly correct, but I remember standing outside my 5th grade classroom window waiting for the teachers to unlock the door. At that time the school doors were only unlocked prior to class starting if there were blizzard conditions, not for cold. The classroom had a thermometer on the window that read -50C at the time. The only reason I remember it was because it was the first time I realized -40C = -40F.

http://en.wikipedia.org/wiki/List_of_Minnesota_weather_recor...