At a Glance

One of the coldest air masses in decades is headed into the Midwest.Daily temperature records will likely be broken.However, most all-time record lows appear out of reach.

The arctic blast that's expected this week is forecast to be one of the coldest air masses to invade parts of the Midwest in at least two decades.

(FORECAST DETAILS: Extreme Cold Coming)

You may have heard some of the buzz about this cold outbreak, including hyperbole about record or even historic cold. But here's the truth.

Daily Record Lows Likely

Daytime high temperatures will be bitterly cold during this outbreak, but we'll focus on forecast low temperatures to make our point.

If you watch a local TV weather segment, you've probably seen a graphic with daily temperature records along with today's actual high and low.

Daily records are simply the highest and lowest temperature recorded at a location on a given day in the station's historical record. For instance, the daily record low at Chicago's O'Hare International Airport for Jan. 23 is minus 19 degrees, set in 1963.

It's likely a number of cities will break daily record lows from this outbreak. In some of these cities in the upper Midwest, it will be their

A few of the potential daily record lows this week include (record-to-beat is shown):

Wednesday: Chicago (minus 15 degrees); Cleveland (minus 4 degrees); Des Moines, Iowa (minus 17 degrees); Detroit (minus 4 degrees)

Thursday: Chicago (minus 12 degrees); Cleveland (minus 4 degrees); Detroit (minus 7 degrees); Pittsburgh (minus 3 degrees)

Forecast Morning Lows

All-Time Record Cold?

You may have heard some speculation about whether this upcoming outbreak may threaten records not just for a specific day, but for any day in a location's historical record.

Here are the all-time coldest temperatures recorded in the same cities as shown in the map above.

The coldest temperatures on record for a sampling of cities.

(Data: NOAA/NWS)

In most of these cities, these frigid temperatures are in another league from the daily records we showed earlier.

In the Dakotas, Minnesota, Iowa and St. Louis, the all-time records still stand from more than 100 years ago.

In Chicago and Detroit, these records were set in the mid-1980s.

A number of Ohio Valley cities – including Cleveland, Columbus, Indianapolis, Louisville and Pittsburgh – set all-time record lows during the mid-January 1994 cold outbreak.

(MORE: America's Coldest Outbreaks)

For now, most all-time cold records appear safe.

That said, a few cities could come within shouting distance of all-time record lows Thursday morning.

This includes Chicago, which may be within a couple of degrees of its all-time record of minus 27 degrees, set Jan. 20, 1985. Cedar Rapids and Waterloo, Iowa, could also dip to near their all-time record lows of minus 29 degrees and minus 34 degrees, respectively.

All this record talk aside, this will be a prolonged bitterly cold outbreak that is likely to be accompanied by at least modest winds at times, which will send .