More counter-examples. Via the Boston Herald.
Minus -27°F, -31°F, -33°F … We’re talking COLD.
18 Dec 2016 – Huron, South Dakota, set a new low for the date of -31°F.
Another record fell in Marshall, Minnesota, where the mercury dropped to -31°F.
Spencer, Iowa’s -27°F was a record-breaker.
Bismarck, North Dakota’s -31°F set a new record low for the 17th of December.
And at -33°F, Linton, North Dakota, was even colder