A January temperature reading of -38°F in Mt. Carroll has been officially verified as the coldest temperature on record in Illinois.
The statewide record low was reported at the NWS Cooperative station in Mt. Carroll, northeast of the Quad Cities, on the morning of January 31st. That’s the same morning the QC International Airport bottomed out at -33°, an all-time record low for the site.
Prior to the -38° reading in Mt. Carroll, the previous Illinois record low was held by a -36° observation in Congerville back in 1999.
State records are verified by the State Climate Extremes Committee. You can read the full report here.