English: This data visualization shows very cold temperatures gripping large portions of North America on Jan. 1, 2018, including the central and eastern United States. A persistent wave of arctic cold has caused temperatures to drop more than 20 to 40 degrees (F) below normal in many locations, bringing one of the coldest starts to a new year in decades. The frigid air is due to an area of high pressure over Alaska and western North America, where relatively warm air has displaced cold, arctic air southward into the lower latitudes. The cold is expected to continue for much of the next week.

From the NOAA Environmental Visualization Laboratory:

This image was created using data from the Global Forecast System (GFS) numerical model, which is used by the National Weather Service to produce forecasts up to 16 days in advance. Darker blue-purple shades indicate the coldest temperatures, while orange and yellow shades indicate warmer surface temperatures. The GFS model is produced by NOAA's National Centers for Environmental Prediction, and contains dozens of variables measured by Earth-orbiting satellites, ranging from temperatures, winds, and precipitation to soil moisture and atmospheric ozone concentration.