Thursday's temperatures tied the hottest July 5 ever and came close to Chicago's hottest day ever, according to the Chicago Tribune.
Temperatures have already hit 102 degrees, tying the record set in 1911. The hottest day in Chicago ever was July 24, 1934 with 105 degrees.
Only twice before has the Chicago area logged three straight days of temperatures in the 100s: July 3-5, 1911 and Aug. 4-6, 1947, according to the Chicago Tribune.
As of 1 p.m., it was 102 degrees at O'Hare International Airport, according to the Trib. At 2 p.m., it was 98 degrees in with a heat index of 102 degrees.
Metra riders will see delays of 10 to 15 minutes Thursday as trains operate at reduced speeds because of the heat.
An excessive heat advisory is in effect until 10 p.m. Friday, according to the National Weather Service.