Relatively mild fall temperatures in early November gave way to an Arctic blast that brought record-setting cold to Iowa and much of the nation.

Temperatures in Iowa averaged nearly 14 degrees below normal from Nov. 11 to 23, and there were some days when temperatures were almost 25 degrees below normal. During this colder period, most of Iowa received the first significant snowfall of the season, and the first subzero temperatures of the season occurred at a few locations. November precipitation...