This past Wednesday the low at the Grand Forks Airport was -17 degrees. Later in the day, a strong surge of mild Pacific air moved across the Red River Valley that pushed the temperature to 39 degrees during the early evening hours that day. That 39 degree high was a record for the date. That difference from morning low to afternoon high was an impressive 56 degrees (Fargo rose 45 degrees that day).
Grand Forks carries two weather data sets. One from the airport going back to 1941 and the other from UND (and now the National Weather Service) that goes back to 1890. I did not have the airport data set handy, but using the UND data set, that 56 degree temperature change would be the second highest observed, behind a 57 degree swing on April 28, 1926 (20 degrees to 77 degrees). This area is known for quick changes in the weather, but even by our standards Wednesday was definitely a day to remember.