Extreme Cold/Wind Chill in Sully, South Dakota

A series of Arctic air masses crossed the region over period of 6 days beginning on Sunday, December 18th. Temperatures failed to even reach 5 degrees above zero during this period, with temperatures consistently dropping into the teens below zero at night. An unusually potent blast of cold air for December followed in behind a reinforcing Arctic front Tuesday night, December 20th, into Wednesday, December 21st, along with a trace to as much as 2 to 3 of new snowfall on top of the pre-existing snow pack. High temperatures on the 22nd were as cold as -12 F in Watertown and -10 F in Aberdeen and Mobridge. Wind gusts of 35 to 55 mph behind this front impacted the region from the 21st through the 23rd, resulting in an extended period of life-threatening wind chills in the -35 to -60 degree F range and ground blizzard conditions for many. The highest recorded wind gusts include 60 mph at Hayes, 58 mph 10 miles south of Bullhead, 54 mph at Vivian, and 53 mph at Agar and Pierre all on the 22nd. The coldest measured wind chills from the 21st into the 22nd include -61 F at Trail City, -59 F at Eureka and 10 miles south of Bullhead, -58 F at Timber Lake, -57 F at McIntosh and 5 miles SE of Selby, and -56 F at Vivian, Foster Bay, Craven, Mac's Corner, Agar, Herreid, and Bowdle; the coldest on the 23rd include -52 F at Eureka, and -50 F at Trail City and 10 miles south of Bulhead.

The extreme cold made the threat to stranded motorists even more dangerous, as numerous roads became impassable. Nearly the entire state was shut down, for the second time this December, as roads were either deemed No Travel Advised or closed by the SDDOT. Numerous vehicle accidents and rescues occurred, and numerous schools closed throughout the event.