WGN-TV meteorologist Tom Skilling is forecasting a high around 100 today, 101 on Thursday and 100 on Friday. The National Weather Service has issued an extreme heat warning for Cook County through Friday evening, and a heat advisory for the collar counties.
Chicago hasn't seen the Fourth of July get this firecracker-hot since it hit 102 degrees in 1911. The record for Thursday is also 102 from 1911, and the record for Friday is 99 set in 1988.
At 11 a.m., it was already 95 at the official recording station at O'Hare International Airport, 97 at Northerly Island, 97 in Waukegan and 94 at DuPage Airport.
The sweltering heat is the product of an expansive mass of hot air that is draped across the country, from the Southwest deserts to the East Coast, and has set several thousand new record temperatures in the past week, according to Skilling.
The sizzling weather has festival organizers adding water attractions as well as emergency medical staff and bottled water to keep crowds cool. In Palatine, Fire Department personnel on bicycles pedaled through the Jaycees Hometown Fest on Tuesday, searching for anyone who was overheated. The festival continues through 5 p.m. Wednesday.
"It feels like you just got out of the shower," said Georgia Orr, owner of Georgie's Greek Tasty Food, a vendor that had employees working in rotations at the grill and using ice packs to cool off.
Jackie Butler, co-chair of Hometown Fest, said officials added two misting hoses and bought nearly 9,000 bottles of water.
In Naperville, organizers of the annual Ribfest, which started Friday and ran through Tuesday, attached a hose to the slide of a popular children's attraction. Barbecue stand workers took turns sitting in the freezer truck.
And the host of a children's show encouraged the kids to join him onstage — provided they wore shoes.
"If you have bare feet you will cook your feet," he warned the audience.
The festival offered three emergency medical service tents, where several visitors stopped each hour to cool off. Medical staff transported four to five people each day to Edward Hospital, with most complaining of heat exhaustion, said Lt. Amy Scheller of the Naperville Fire Department.
Scheller cautioned Fourth of July revelers to stay hydrated as the heat wave continues.
"Anyone is susceptible if they don't prepare," she said.
Lake Michigan often can take the edge off high temperatures in areas near the water, but that hasn't been the case recently. Even at night, temperatures in Chicago have remained in the 80s while water temperatures along the shoreline have been in the mid-70s, according to Castro of the weather service.
The high temperatures are the result of a slow-moving dome of heat over the center of the country, he said, adding that normal highs are in the mid-80s.
At Navy Pier, dozens of people armed themselves with water bottles and ice cream to try to keep cool. Children used a more direct approach, splashing in the large fountain near the front entrance.
Navy Pier officials anticipated large crowds Wednesday at the air-conditioned IMAX Theatre and Chicago Children's Museum.
In a tiny lemonade and nut stand on the pier, Alfonso Delgado, 28, did his best to abide by three rules: drink water, munch on ice chips and sit still.