CHICAGO -- Midwest residents woke Tuesday to the whir of fans and air conditioners, the soundtrack to an unusually intense heat wave enveloping most of middle America and slowly spreading eastward.
From Texas to the Dakotas, and east to Illinois and Indiana, temperatures and humidity levels soared on Monday and were expected to remain high through at least the end of the week, by which time forecasters say the East Coast will get to share the misery.
Seventeen states issued heat watches, warnings or advisories on Monday, when the heat index easily surpassed 100 degrees in many places, including 126 in Newton, Iowa, and 119 in Madison, Minn.
Things were heating up on the East Coast on Tuesday, and the National Weather Service said temperatures in New Jersey that were expected be in the lower 90s and could reach 100 degrees by the end of the week.
Cooling centers were set up in many cities to offer residents places to escape, and they were expected to remain open during the day until the heat abates.
Chicago opened six centers and encouraged residents to go to hundreds of public buildings, including libraries and police stations.
Anne Sheahan, spokeswoman for the city's Department of Family and Support Services, expected the number of people seeking refuge at the centers to climb in step with the temperatures, which were not expected to drop below the mid- to upper-90s throughout the week. The city was also offering rides to cooling centers.
Chicago authorities stepped up their high-heat precautions after a 1995 heat wave killed more than 700 people in less than a week. Now temperatures above 90 degrees trigger an emergency plan that includes city workers calling and visiting the frail and elderly.
In East St. Louis, Ill., a mostly black city that's among the nation's poorest, 79-year-old Bernice Sykes spent Monday in a soup kitchen that had been pressed into service as a makeshift cooling center.
Sykes, a retired restaurant worker living on Social Security income, figured she had little choice to seek relief: One of her two tiny fans failed Sunday in her $500-a-month-efficiency apartment, which has no air conditioning.
"I want to get out of there as quick as I can," she said Monday. "Right here, I feel good. But I've got to use that one fan when I get home. It's just so hot."
As with any heat wave, electricity usage has spiked as homes and businesses cranked up their air conditioners.
In Ames, Iowa, where temperatures were expected to hit 95 degrees on Tuesday, the electricity service asked residents to cut back because of high demand, suggesting they turn off unused electrical devices, close drapes during the day and wash clothes in the early morning or evening, after peak usage hours.
In Wisconsin, where the heat index was expected to be in the 100s again Tuesday, the Wisconsin Public Service Corp. said it didn't expect brownouts or blackouts despite the high usage, but it warned that customers should expect to pay more on their next bills.
Utilities suggested using fans, instead of air conditioners, to save energy and money. But the heat has been so intense in many areas that even powerful fans didn't cut it.
"When its 95 degrees out, and the fans blow out hot air that's not enough to drive down body heat," Dr. Bobby Mukkamala, who lives in a suburb of Flint, Mich., said Monday.
Associated Press writers from throughout the region contributed to this report.
This animation provided by NOAA shows the predicted daily high temperatures from July 13-21: