(CNN) -- Much of the central and eastern United States will bake under intense heat Friday, prompting warnings about air quality and fears about the health of those unable to find refuge in cooler confines.
The blistering conditions won't be fleeting: High temperatures not only are expected to be around or above 100 degrees in locales from Topeka, Kansas, to Washington on Friday, but they're expected to stay at about that level in many places through next week if not longer.
"Heat-related illness such as heat exhaustion or heat stroke are a real threat; dehydration can occur quickly," noted the National Weather Service's bureau in Indianapolis, where highs should hit 101 on Friday, while issuing an excessive heat warning. "The extended period of heat also will cause drought conditions to worsen and raise the concern for wildfire development."
The thermostat in St. Louis is forecast to hit 108 degrees and remain above 100 through next Thursday, at least, according to the weather service.
That's prompted the city health department to remind residents to limit outdoor activities, not to leave children or pets in vehicles and to watch out for signs of heat exhaustion.
In Memphis, Tennessee, where highs should hit 104 degrees on Friday with a heat index closer to 108, firefighters will be going door to door checking on residents to make sure they're braving the weather well. Churches and faith-based institutions are also being urged to reach out to people and to ask people to check on their neighbors and relatives.
"Please, if you know of someone who doesn't have air conditioning or who might be struggling with the heat, just stop by and see how they are doing," Mayor A.C. Wharton, Jr., urged residents in a press release.
A "code red smog alert" has been declared Friday for metro Atlanta, the first of its kind since 2010, according to the Clean Air Campaign, a partnership between employers and the state transportation department.
Other metro areas on the East Coast will also feel the heat. Philadelphia and Washington both will have highs near 100 on Friday, while New Yorkers should see temperatures soar into the high 90s.