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CHICAGO — A dangerous and potentially deadly heat wave threatens much of the continental United States, including Chicago, with dozens of record high temperatures both in the daytime and in the evening expected this weekend.
The storms pushed back the start time of the National Weather Service's Excessive Heat Warning for the Chicago area, which will now go into effect at 10 a.m. Friday and last until late Saturday.
Over 700 flights have been canceled at O'Hare International Airport due to storms moving through the Chicago area. As of 2 p.m. Thursday, delays were averaging about 45 minutes at O'Hare and about 60 flights were canceled at Midway International Airport, with delays averaging about 15 minutes.
To track the storms, check out WGN's interactive radar here.
Chicago Mayor Lori Lightfoot said the city is ready to help those in need of relief, but reminded everyone to look out for each other. To find a cooling center near you, go to wgntv.com/coolingcenters.
Illinois transportation officials warned drivers throughout the state to watch for road blowouts during the intense heat.
Acting Transportation Secretary Omer Osman said the "potential for pavement failures will increase" this week as the heat index likely tops 100. High temperatures can cause roads to expand and blow out.
State crews will be monitoring the conditions and can make repairs as quickly as possible. In the Chicago area, Metra trains will be reducing their speed by 10 mph. Chief Executive Jim Derwinski said steel can expand in high heat, causing track problems.
Pavement failures can be reported to (800) 452-4368 or 911.
Heat affecting more than just Chicago area
More than 150 million people in nearly 30 states were under a heat watch, warning or advisory on Thursday morning, according to CNN meteorologist Dave Hennen.
Over the next few days, more than 85 percent of the lower 48's population will see temperatures above 90 degrees Fahrenheit, Hennen said, and more than half will see temperatures in excess of 95 degrees.
Much of the heat expected for Thursday was forecast to descend on the Midwest and Mississippi, before making its way to the Northeast on Friday and Saturday, Hennen said.
On Thursday, cities under excessive heat warnings included Chicago, Oklahoma City, Omaha, St. Louis, Indianapolis, Detroit and Philadelphia.
Minneapolis, Little Rock, Memphis, Nashville and Raleigh were all under heat advisories.
Cleveland, Pittsburgh, Washington, Baltimore, New York and Boston were all under excessive heat watches and expected to see high temperatures this weekend.
Nighttime cooldown? Not much
The extreme temperatures overnight are an important and dangerous threat, because it means peoples' bodies and homes will not have the opportunity to cool off.
"Even after the sun goes down, the temperatures will not drop much below 80 degrees," said Rich Guidice, executive director of Chicago's Office of Emergency Management, "offering little to no relief."
The heat wave has prompted the city of Chicago to open cooling centers throughout the city for anyone looking for relief.
Chicago officials warned residents to look out for signs of heat exhaustion and heat stroke, including cramps, feeling weak and nausea.
Residents should not hesitate to call 911 if they believe they are suffering from heat stroke, said Dr. Allison Arwady, the acting commissioner of the Chicago Department of Public Health.
According to meteorologists, the heat wave will encompass much of the eastern half of the country into the weekend, before a cold front should bring relief late Sunday and into early next week.
Heat wave made worse by climate crisis
Experts say the heat wave is only made worse by the ongoing threat of climate change. According to last year's National Climate Assessment, the number of hot days in the US is increasing.
Heat waves have also increased in frequency, rising from an average of two per year to six per year in the last five decades. The threat is especially pronounced in the Northeast, where "the frequency, intensity, and duration of heat waves is expected to increase" due to climate change.
By 2050, the Northeast can expect approximately 650 more deaths each year because of extreme heat, the assessment found.
The Associated Press contributed to this report.