The current cold wave is impressive in its length and severity. However, it is hardly unprecedented. The average daily mean temperature for the past seven days in Fargo is minus 12, and minus 15 in Grand Forks, and the temperature has failed to rise above zero. Relative to other cold weather streaks here, though, this one is not so bad.
In Fargo, the average daily mean temperature Feb. 3-9, 2007, was 13 below zero. The average from Jan. 27 to Feb. 2, 2004, was minus 17. The average from Jan. 30 to Feb. 5, 1996, was minus 22. The same periods in Grand Forks averaged minus 16, minus 20 and minus 22, respectively.
The Fargo record from the 1880s (it was Moorhead then) indicates at least a couple seven-day periods around 15 degrees colder per day than what we've experienced this past week.