Authorities say at least 21 people have died in a deep freeze spreading from the US midwest to the east and south.
There have been record low temperatures from Boston to Birmingham, with some areas xperiencing temperatures colder than much of Antarctica.
All 50 states saw freezing temperatures at some point on Tuesday, including Hawaii, where it was -8C (18F) on top of Mauna Kea, a dormant volcano.
The big chill started in the midwest over the weekend, and by Tuesday it covered about half of the country.
In New York City, the high was expected to be -12C (10F), and in Boston, around -8C (18F).
Across the south, Birmingham, Alabama, dipped to a low of -14C ( 7F), breaking the record of -11.7C (11F) set in 1970.
The deep freeze dragged on in the midwest as well, with the thermometer reaching -24C (-12F) overnight in the Chicago area.
The cold turned deadly as authorities reported at least 21 cold-related deaths across the country since Sunday, including seven in Illinois, and six in Indiana.
At least five people died after collapsing while shovelling snow, while several victims were identified as homeless people who either refused shelter or did not make it to a warm haven soon enough to save themselves from the bitter temperatures.
Forecasters say warmer conditions should return in the next day or two.