Winter Safety and Preparedness

It's Official: Illinois Set a New All-Time Record Low During January's Polar Vortex Cold Outbreak

At a Glance

An Illinois town's low temperature during a January cold outbreak was confirmed to be a new state record.
Mt. Carroll, Illinois, plunged to minus 38 degrees on January 31, 2019.
This bested the previous state record set in 1999.
An ad hoc committee of meteorologists examined the instruments and determined the data was valid.

One of the coldest temperatures measured during the late January 'polar vortex' cold outbreak has been accepted as a new all-time record for the state of Illinois.

A committee of meteorologists and climatologists concluded Wednesday that the low of minus 38 degrees recorded in Mt. Carroll, Illinois, on January 31, was valid and thus set Illinois' new all-time record coldest low, besting the previous record of minus 36 degrees near Congerville on Jan. 5, 1999.

Mt. Carroll is about 240 miles west-northwest of downtown Chicago, near the Mississippi River in northwest Illinois.

(RECAP: January 2019 Was the Coldest Arctic Outbreak in at Least Two Decades)

According to the final report on the event from the State Climate Extremes Committee, the frigid low was consistent with the overall meteorological setup featuring clear skies, light winds and snow cover that typically produces extreme low temperatures in winter.

They noted the location of the Mt. Carroll instrumentation sits in an area of relatively low elevation on the city's west side near Carroll Creek. Since it is more dense, cold air drains and settles into the lowest elevations, such as valleys, on nights with light winds.

Seven other locations near Mt. Carroll also reported lows in the minus 30s that morning, eliminating the possibility the Mt. Carroll reading was an egregious outlier.

The National Weather Service in Davenport, Iowa, which serves northwest Illinois, confirmed the instrumentation was in good working order and that proper procedures were followed. Daily temperature observations have been taken in Mt. Carroll since 1897.

(MORE: Itching For Spring? Here's When Temperatures Typically Warm Up)

At least four other locations set all-time record lows during the late January cold outbreak.

More recently, all-time March record lows, including a potential all-time March state record, were set in Montana.