A dangerous and oppressive heat wave is forecast to scorch the central and eastern US over the next few days, with record high temperatures possible in the Northeast.
The worst of the heat will start in the Midwest on Friday before creeping its way east toward the Northeast and Mid-Atlantic by Saturday and Sunday.
Temperatures of 100 degrees will bake parts of the central and southern Plains into Friday, according to AccuWeather.
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The hot weather is courtesy of a strong upper-level ridge of high pressure, sometimes known as a "heat dome," which will park itself over much of the U.S. by the weekend, according to the Weather Channel.
In urban areas of the major cities, such as Chicago, St. Louis, Detroit and Cincinnati, cooling stations will be needed, AccuWeather warned. The vast expanse of concrete and pavement will give off heat at night and make sleeping difficult without air conditioning.
In Chicago, the heat index – how hot it feels when humidity is added in – could reach 115 degrees Saturday, the National Weather Service said.
The weather service in Kansas City tweeted to "limit time outdoors, wear light colored and light weight clothing, take frequent breaks preferably in the shade, and drink plenty of water."
In Milwaukee, Bell Ambulance is preparing for a spike in heat-related calls on Friday as the heat arrives.
"We are adding extra crews to the street," said Scott Mickelsen, a critical care paramedic and director of client services for Bell. "All of us in management will be on ambulances as well."
All of the company's rigs will be stocked with ice, water and Gatorade for ambulance crews, "because if our responders aren't safe and healthy, they can't help people."
Organizers of rallies to protest the Trump administration's "zero tolerance" policy on immigration, planned in all 50 states Saturday, should be prepared to deal with the extreme heat. Cooling centers, bottled water and emergency medical care should be made available.
The biggest rally, in Washington, D.C., will be held under blazing sunshine and temperatures in the low to mid-90s, the weather service said.
Record heat is possible Sunday in cities such as Syracuse and Buffalo in New York, and in Burlington, Vermont, the Weather Channel said.
A few spots could reach 100 degrees Sunday, including Syracuse, which has only done so 10 times since 1902.
Smoggy air will add to the misery: "Extended periods of sunny, hot, humid and calm weather are the perfect breeding ground for poor air quality conditions," according to AccuWeather meteorologist Faith Eherts.
Some slight relief is forecast as swath of thunderstorms advances from the northern Plains later this weekend into early next week. As a result, it should not be as oppressive by the Fourth of July over the Midwest.
In the Northeast, temperatures are expected to trend downwards slightly Tuesday and Wednesday. However, no significant cooling trend is in sight.