Wednesday's scorching heat was a test of endurance for festgoers and parade watchers -- and those who've been without power for days after Sunday's storms.
It's even prompted an unusual decision by officials at Arlington Park Racecourse.
The post time for Thursday's first race will be 5 p.m., rather than the standard 1 p.m.
"By starting our races at 5 p.m. on Thursday, we can avoid the worst of the heat," track General Manager Tony Petrillo said in a news release.
Gates will open at 11:15 a.m. as usual. Friday's and Saturday's racing schedules have not been changed.
Temperature readings at O'Hare International Airport reached 102 degrees by midafternoon, tying the record high July Fourth temperature set in 1911, according to the NOAA.
According to weather.com, it felt like 104 degrees at its worst Wednesday. An excessive heat warning will remain in effect until 6 p.m. Friday, the website reported.
It wasn't so bad if you were somewhere with air conditioning, but plenty of places -- especially in central DuPage County -- had none because of continued power outages that began Sunday.
Roughly 8,180 ComEd customers were still without electricity mid-Wednesday afternoon, a company spokeswoman said.
Most of the customers still without service were in ComEd's northern region, with the majority clustered in DuPage County towns such as Wheaton, Addison, Lombard and Glen Ellyn, spokeswoman Arlana Johnson said.
A smattering of outages continued in Chicago and neighborhoods in the near-West suburbs, too, Johnson said.
Electricity has been restored to more than 300,000 customers since the storm, Johnson said.
Most of the affected neighborhoods were expected to have electric service restored by Wednesday night. Some isolated areas with more extensive storm damage -- particularly in those DuPage County towns -- may have to wait until Thursday to have power again.
An estimated 600 crews were on the job Wednesday despite the national holiday. That number included workers from neighboring states such as Missouri, Wisconsin and Iowa.
Some ComEd employees voluntarily came back from planned vacations early to help restore electricity, Johnson said.
Although some suburbs had canceled fireworks shows planned for this week because of fire hazards increased by the dry conditions on the ground, Independence Day parades went on as scheduled across the region. No significant weather-related problems were reported.
The forecast is calling for temperatures in the triple digits for the next two days, an an extreme heat advisory has been issued. The highs today will be 100-105 with heat indices peaking between 107 and 113 this afternoon.