Brutal cold: Is this really unusual or just a bout of winter weather?

Arctic air is once again sweeping the nation east of the Rockies, hitting the East and mid-Atlantic states with frigid weather, with temperatures on average 20 to 30 degrees below normal throughout the region, according to the National Weather Service.

In Chicago, a wind-chill warning shut down hundreds of schools Monday, commuters have been hit with public transit delays, and about 400 flights at Chicago O’Hare International Airport have been canceled, according to the Chicago Tribune.

And that’s just the beginning.

Wind chills are expected to drop to minus 40 on Monday night and Tuesday in Chicago. Farther north, residents in Northern Minnesota and Wisconsin are bracing for minus 50 until noon Tuesday.

Although this third round of Arctic chill this month may seem odd, it’s actually not unusual compared with past years. It probably will not go down as one of the 10 coolest Januaries on record.

Why?

The Los Angeles Times asked Brian Hurley, a meteorologist and lead forecaster for the National Weather Service in Maryland, to give some perspective.

Is this cold snap particularly brutal or just normal winter weather?

The frigid systems that have swept through the region have been transient and there have been some breaks. While there have been some days of bitter cold, they are brief and haven’t lasted all month. So, while there have been days with below-average normal temperatures, the average monthly temperatures are not that unusual.

This is the time of year where you expect this type of chill.

For instance, as of Monday, January’s monthly average temperature in Chicago so far is 16.5 degrees. The average is around 24 degrees. That’s about 7.5 degrees below the average.

In the past, Januaries have averaged up to 15 degrees below normal.

Why is it so cold now?

A cold air system is moving from central Canada into the Central Plains and currently impacting the Northeast, mid-Atlantic states and the upper Midwest, including Louisiana and Texas.

How long will it last?

This chill is also going to be fairly transient. Much of the chill should be gone by Wednesday. By Thursday, residents in most impacted areas should see normal or even above-normal temperatures. By Friday, most of the nation should be at normal temperatures.

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