The polar vortex is crashing into U.S. territory, delivering the coldest weather to the Lower 48 in decades.

From eastern Montana to the Great Lakes, this historic blast of cold will be downright dangerous – with widespread wind chills of 5o-60 below zero (isolated 70 below zero readings are possible Monday morning). That’s cold enough to produce frost bite in minutes and is truly life-threatening for anyone caught out in the elements without suitable cover.

Here are 10 images that offer a sense of how widespread and severe this cold snap is…

1) Astonishing 135-degree spread in “feels like” (apparent) temperature across Lower 48 Sunday afternoon (3 p.m. central): from 79 degrees in south Florida to 56 below zero in northern North Dakota

2) Approximate 115 million people under wind chill warning, watch or advisory as of this morning

3) Monday morning’s wind chill forecast from the National Weather Service: 40 below or colder wind chills span from Chicago to eastern Montana. 50 below or colder wind chills span from central Wisconsin through Minneapolis and into North Dakota.

4) Monday’s high temperatures in Midwest from European model: Widespread 10 below or colder for highs (these are actual air temperatures, not wind chills)

5) Tuesday morning’s wind chill forecast from the National Weather Service: approximately 1.5 million square miles or half of the lower 48 is forecast to have wind chills below zero, including Little Rock, Atlanta, Richmond and Washington, D.C.

6) Tuesday morning’s jet stream from Earth visualization – showing polar vortex with upper level winds straight from the north pole wrapping into it

7) Tuesday’s low temperatures will be up to 40 degrees below normal in the East

8) In Washington, D.C., the temperature may drop 40 degrees in 24 hours – from around 48 at 1 a.m. Monday morning to the single digits at 1 a.m. Tuesday morning.

9) What happens to boiling water passing through a squirt gun at 42 below? (hat tip: WattsUpWithThat – from northern Ontario, January 2)

10) What happens to your body at extreme temperatures (infographic via Twitter)

Video: ‘Life-threatening’ cold bites U.S. Midwest

As the Midwest braces for the coldest weather it's seen in two decades, forecasters warn the Arctic cold temperatures could be life-threatening. (Reuters)