Early on Friday, the core of the cold air mass, driven from Arctic Canada into the United States by high-altitude air currents, was centered over the U.S. Plains, said weather service forecaster Bob Oravec. International Falls, Minnesota, was the coldest spot as of 7 a.m., with temperatures hovering around -36 F (-38 C). "It's moving into the Northeast" and temperatures will drop throughout the day on Friday, he said. By comparison, air temperatures in Eureka, Canada's northernmost Arctic weather station, were hovering at -41 F (-41 C) on Friday morning. Boston was about 22 above zero F (-6 C) on Friday morning, with temperatures expected to plummet throughout the day and hit -3 F (-19 C) by midnight.

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