CHICAGO (WLS) --Isolated thunderstorms offered some temporary relief on what was forecast to be the hottest day of a heat wave impacting the Chicago area.
While the thunderstorms kept temperatures from rising above 90 in Chicago, an Excessive Heat Warning for northern Illinois and southern Wisconsin and a Heat Advisory for northern Indiana and southwest Michigan remains in effect from 12 p.m. Thursday to 7 p.m. Friday, the National Weather Service said.
The Excessive Heat Warning has been extended to 7 p.m. Saturday for counties south of the city, including: Ford, Grundy, Iroquois, Kankakee, LaSalle, Lee, Livingston, and Ogle.
Early Thursday evening, heat index values ranged from 100-110 degrees in the northwest and southwest suburbs. Due to the thunderstorms, heat indices were dramatically cooler along the lakefront, ranging from 72 degrees in Michigan City, Ind., to 93 degrees in Waukegan. Check out the latest heat index readings from the weather service HERE.
Watch the latest forecast from the First Alert Weather Team:
Metra officials warned riders that there could be delays due to the heat later this week. When temperatures exceed 95 degrees, conductors will reduce speed to 10-15 miles per hour to compensate for heat-related stress on tracks and signals. The slower speeds could mean delays up to 10-15 minutes, Metra said. Thursday morning, Metra crews repaired a cracked rail on the inbound Union Pacific Northwest Line in Mount Prospect.
The Chicago Shakespeare Theater tweeted that Thursday night's performance at Tuley Park was canceled.
High temperatures will be in the 90s through Sunday. Residents should plan ahead, have a cool place to take shelter, avoid outdoor activity during the afternoon, drink plenty of fluids and check on relatives and neighbors.
"If there's a sick person or an elderly person in your community or your neighbor, if you could, please check on them. Take care of yourself, but also reach out and be a good neighbor," Mayor Rahm Emanuel said.
"We really do have to be careful and make sure we're drinking plenty of water. Not necessarily caffeinated beverages, not necessarily sugar-sweetened beverages, not necessarily alcohol. Just water is really, really important," said Dr. Julie Morita, Chicago Dept. of Public Health.
City public safety officials urge residents to avoid direct sunlight and to try stay indoors during the extreme heat - especially at midday, the hottest part of the day. It can sometimes be hard for people to realize when they've become overheated.
"You just generally feel like it's a lot harder than it should be. Maybe you're dehydrated or something. All of a sudden it's too late to re-hydrate and you just have to stop and walk it and get home or jump in the lake," said Mike Malloy, a runner.
Dr. Michele Bailey, an internal medicine expert at Rush University Medical Center, explained how to prevent heat-related illnesses.
Drivers should watch out for buckled pavement, which can happen when temperatures rise. Motorists with children and pets should also keep a close eye on them during the heat wave and make sure not to leave them inside their vehicles - even for a short period of time.
A 4-year-old girl from northwest suburban McHenry was hospitalized after she was found inside a hot car. The McHenry County Sheriff's Office said she got into the vehicle on her own. Her parents found her unresponsive about 20 minutes later.
Rich Guidice, of the Office of Emergency Management and Communications, joined ABC7 News This Morning to explain the steps the city is taking to keep people cool and safe.
There are places in Chicago where people can go to get some relief from the heat. Cooling centers are open across Cook County. The City of Chicago also operates six cooling centers during the summer months.
The Garfield Center, located at 10 S. Kedzie, is available 24-hours a day, seven days a week to connect residents to emergency shelter. Residents are advised to contact the cooling center they plan to visit ahead of time to make sure it is open.
The air conditioning was cranked up so high at Chicago's Southwest Regional Center Thursday that condensation fogs up the windows. Visitors don't seem to mind.
"It's good to be in here today. The heat drags me down when I'm outside! I'd rather be somewhere where it's really cool," said Clarissa Land, who stopped in for a break from the heat.
Here are the best tips to stay safe during the hot summer months:
The senior center is one of the dozens of cooling centers open the public on this very hot day. Mayor Rahm Emanuel stopped by and reminded everyone to stay hydrated and out of the sun.
"If there is a sick or elderly person in your neighborhood, please check on them," Emanuel said.
The following cooling centers are open from 9 a.m. to 5 p.m. Monday through Friday:
1140 W. 79th Street
Chicago, IL 60621
10 S. Kedzie Ave.
Chicago, IL 60612
4314 S. Cottage Grove
Chicago, IL 60653
North Area Center
845 W. Wilson Ave.
Chicago, IL 60640
South Chicago Center
8650 S. Commercial Ave.
Chicago, IL 60617
Trina Davila Center
4312 W. North Ave.
Chicago, IL 60639
COOK COUNTY SUBURBS
Berwyn Library, 2700 S. Harlem, Berwyn;
Berwyn Police Department, 6401 W. 31st, Berwyn;
Bloom Township Village Building, 425 S. Halsted, Chicago Heights;
Bremen Township Community Cneter, 15350 S. Oak Park, Oak Forest;
Bremen Township Administrative Office, 16361 S. Kedzie Pkwy. Markham;
Calumet Township Community Center, 12633 Ashland, Calumet Park;
Cicero Village Building, 4949 W. Cermak, Cicero;
Cicero Police Office, 4901 W. Cermak, Cicero;
Cicero Public Safety Building, 5410 W. 34th St., Cicero;
Cicero Community Center, 2250 S. 49th Ave., Cicero;
Elk Grove Township, 2400 S. Arlington Hts., Arlingotn Heights;
Hanover Township, 240 S. Illinois Rt. 59, Bartlett;
Leyden Township, 2620 N. Mannheim, Franklin Park;
Lyons Township, 6404 W. Joliet Rd., Countryside;
Maine Township, 1700 Ballard Rd., Park Ridge;
Niles Township, 5255 Main St., Skokie;
Norwood Park, 7833 W. Lawrence, Norridge;
Oak Park, 130 S. Oak Park Ave., Oak Park;
Orland Township, 14807 Ravinia Ave., Orland Park;
Palatine Township, 721 S. Quentin Rd., Palatine;
Palos Township, 10802 S. Roberts Rd., Palos Hills;
Proviso Township, 4565 Harrison St., Hillside;
Riverside Township, 47 Riverside Rd., Riverside;
Stickney Township, 7745 S. Leamington, Burbank;
Barrington Public Safety Building, 400 N. Northwest Hwy., Barrington;
Barrington Train Station, 201 S. Spring St., Barrington;
Wheeling Township, 1616 N. Arlington Heights Rd., Arlington Heights; and
Worth Township, 11601 S. Pulaski Rd., Alsip.
FULL LIST: Cook County cooling centers
The Sun-Times Media Wire contributed to this report.