Five facts about the US cold snap:
- At -38C, Babbitt, Minnesota has been colder than Mars in recent days. It was also the coldest place in the United States on Monday according to the National Weather Service.
- People have been warned frostbites could set in on uncovered skin within minutes if they go outside.
- Some 4,000 flights were canceled and 7,500 delayed, according to FlightAware.com, which tracks airline activity.
- Temperatures were 11 to 22C below average in parts of Montana, North and South Dakota, Minnesota, Iowa, Wisconsin, Michigan and Nebraska.
- The coldest temperatures in years and gusty winds were expected as far south as Brownsville, Texas, and central Florida, the National Weather Service said.