Extremely cold air moved across northern Illinois during the evening of January 29th and continued through midday on January 31st.  Air temperatures were below zero for 52 consecutive hours at Chicago O'Hare Airport, making it the 4th longest stretch of hours below zero at Chicago.  Chicago O'Hare set a daily record low of -23 on the morning of January 30th and -21 on the morning of January 31st.  Rockford set their all time record low temperature of -31 on the morning of January 31st, with a low of -25 on the morning of January 30th and -16 on the evening of January 29th.  Air temperatures were below zero for 57 consecutive hours at Rockford Airport, making it the 9th longest stretch of hours below zero at Rockford.
Other low temperatures on the morning of January 31st included: -32 at Sugar Grove (ARR); -31 at Rochelle (RPJ); -29 at West Chicago (DPA); -28 at Barrington; -25 at DeKalb (DKB); -24 at Lansing (IGQ); -23 at Waukegan; -23 at Joliet (JOT) and -22 at Dwight.
The lowest wind chills occurred during the morning of January 30th.  The lowest observed wind chills were -56 at DeKalb; -55 at West Chicago; -54 at Pontiac, Rochelle and Sugar Grove; -53 at Morris, Peru and Romeoville; -52 at Chicago O'Hare and Kankakee; -51 at Chicago Midway, Rockford Airport, Lansing; -50 at Chicago Northerly Island; -48 at Wheeling and -45 at Joliet and Waukegan.

Extreme Cold/Wind Chill in WILL, ILLINOIS
From 29-JAN-19 22:15:00 to 31-JAN-19 10:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in LA SALLE, ILLINOIS
From 29-JAN-19 21:55:00 to 31-JAN-19 09:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in LIVINGSTON, ILLINOIS
From 29-JAN-19 22:55:00 to 31-JAN-19 01:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in KANKAKEE, ILLINOIS
From 30-JAN-19 00:35:00 to 30-JAN-19 23:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in FORD, ILLINOIS
From 30-JAN-19 00:00:00 to 30-JAN-19 23:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in IROQUOIS, ILLINOIS
From 30-JAN-19 00:00:00 to 30-JAN-19 23:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in LAKE, ILLINOIS
From 29-JAN-19 23:55:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in WINNEBAGO, ILLINOIS
From 29-JAN-19 21:54:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in BOONE, ILLINOIS
From 29-JAN-19 22:00:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in LEE, ILLINOIS
From 29-JAN-19 19:35:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in OGLE, ILLINOIS
From 29-JAN-19 19:35:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in DE KALB, ILLINOIS
From 29-JAN-19 19:55:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in MCHENRY, ILLINOIS
From 29-JAN-19 22:00:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in KANE, ILLINOIS
From 29-JAN-19 18:52:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in DU PAGE, ILLINOIS
From 29-JAN-19 21:52:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in COOK, ILLINOIS
From 29-JAN-19 22:51:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in KENDALL, ILLINOIS
From 29-JAN-19 22:00:00 to 31-JAN-19 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Extreme Cold/Wind Chill in GRUNDY, ILLINOIS
From 29-JAN-19 22:35:00 to 31-JAN-19 09:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS