Heat advisories and warnings were transferred eastward Tuesday, as temperatures were expected to reach into the triple digits this week in Washington, New York, Philadelphia, Baltimore and some southern Plains states.

After a major power outage caused over 3,400 households to lose power in Chicago, hundreds of housing residents on the city's South Side were evacuated from buildings early Tuesday as temperatures reached into the 90s for the fifth day in a row.

Illinois officials blamed three deaths on the heat. At least 2,775 of the affected households and other customers remained without power Tuesday morning. Power officials said it was not definite the heat wave had anything to do with the outage, but did predict record demand as people cranked air conditioners and fans to the max.

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"It's a mess," said Lenora Stinson, 47, who was in an 11th floor apartment when the power died. "It's a big mess. Everybody's panicking — they don't know where they're going."

About 350 of the most fragile evacuees were taken to hotels and 600 others were taken to the nearby McCormick Place convention center, said Fire Department spokesman Larry Langford.

By midafternoon Tuesday, the temperature in Chicago was 100, Baltimore reached 99 and Washington hit 97, though the humidity made it feel like 107. In New York's Central Park, it was 95; the record for the date was 100, set in 1933. The National Weather Service said the mercury could reach 104 on Wednesday, and Thursday could be bad, too.

The blistering temperatures also scorched Conyers, Ga., where a high school football player died one day after collapsing at practice.

"It's going to be very difficult to breathe. The air is going to be very thick," said Nancy Figueroa, a meteorologist with the National Weather Service. "The young and the old should be very careful to stay in cool places, because it's very dangerous."

With a disastrous 10-day power outage in Queens still fresh in memory, the city adopted energy conservation measures. Thermostats in city offices were set at 78, and large municipal installations such as the Rikers Island jail used backup generators.

The giant Pepsi-Cola sign on the Brooklyn waterfront was to be dimmed, as were the lights illuminating the George Washington Bridge, the Brooklyn Bridge and other spans.

The heat index, a measure of temperature plus humidity, was issued an air stagnation advisory and an excessive heat warning for parts of Tuesday and Wednesday.

Gary Waxman fortified himself with towels and extra T-shirts Tuesday morning as he headed to work at his unair-conditioned newsstand in suburban White Plains.

"I'm ready for the wrath of nature," Waxman said.

In upstate New York, thermometers hit 90 degrees before noon, and were expected to reach as high as 102. Two small fans set to "high" did nothing for parking lot attendant Isaiah Bishop in Syracuse, N.Y.

Faced with predictions of triple-digit temperatures, Mayor Michael Bloomberg signed a heat emergency order Monday directing city agencies to take additional steps to protect residents.

"I urge all New Yorkers, especially seniors, to try to beat the heat by drinking plenty of water, staying out of the sun, avoiding strenuous activity, and taking advantage of city cooling centers and public pools," Bloomberg said.

Click here to read more about New York's cooling centers.

Heat exhaustion symptoms include heavy sweating, weakness, headache, weak pulse, dizziness, exhaustion, fainting, nausea or vomiting, and cold, clammy skin. Body temperature will seem normal.

Heat stroke symptoms include flushed, hot, dry skin, weak or rapid pulse, shallow breathing, lack of sweating, throbbing headache, dizziness, nausea, confusion, and unconsciousness. Body temperature will be elevated. Victims should get immediate medical attention.

Meanwhile, city officials were trying to curb the use of excessive power to avoid any chance of a blackout. For example, the necklace lights that decorate East River bridges were scheduled to go back on this week but now will remain dark indefinitely, officials said. They were turned off during a 10-day blackout that affected an estimated 100,000 people in parts of northwest Queens.

The New York Independent System Operator, which controls the state power grid, predicted record demand but spokesman Ken Klapp said the state should have enough electricity, barring equipment problems.

Things weren't much better in other parts of the country.

Heat that blistered California last week hung over the Midwest on Monday, prompting communities to throw air-conditioned buildings open to the public and endangering millions of people with outdoor jobs.

Temperatures across the Midwest and Plains flirted with or exceeded 100 degrees, and the heat index — a measure of temperature plus humidity — passed 110 degrees in spots. The National Weather Service issued heat warnings for such cities as Chicago; Cincinnati; Dayton, Ohio; and Tulsa, Okla.

The Midwest could get some relief by Wednesday, but the worst of the heat was expected to drift east on Tuesday, bringing scorching temperatures to New York, Washington and Boston.

In Cleveland, temperatures climbed so high by evening rush hour that the city closed a bridge over the Cuyahoga River because the heat was causing the steel to expand and the bridge's parts could not fit properly together.Ohio farmers used fans and cold showers to keep their cattle cool. Even with those efforts, the animals produced about 10 pounds less milk per day because of the heat, said farmer Clark Emmons of Fayette, Ohio.

In California, the sweltering heat that punished the state for two weeks subsided, but the number of confirmed or suspected heat-related deaths climbed to 164 as county coroners worked through a backlog of cases.

In Chicago, officials made available a special telephone line to request checks on vulnerable neighbors and friends. The Department of Human Services and police responded to nearly 50 such requests by early Monday. The city's Department of Aging also telephoned more than 300 senior citizens to offer help, such as rides to cooling centers.

The Cook County medical examiner's office reported two heat-related deaths in suburban Chicago on Monday. Both victims were men with heart disease, which contributed to their deaths along with heat stress. And authorities told the (Peoria) Journal Star that a 39-year-old man central Illinois man whose family said he took medication that prevented him from sweating died Monday after falling asleep in the small trailer where he lived.

In Oklahoma, authorities reported two more deaths that happened over the weekend. In Missouri, at least 14 deaths since July 12 are blamed on the heat after a 71-year-old woman died in St. Louis during the weekend, Brian Quinn, a spokesman for the Missouri Department of Health and Senior Services, said Monday.

Colonial Downs, a horse track in New Kent County, Va., canceled racing because of the 100-degree heat. But gamblers still could take refuge in the air-conditioned simulcasting area, where they could watch and bet on races taking place elsewhere.

Joe Calandro, a mechanic in New Haven, Conn., worked on an Oldsmobile with an electrical problem. Despite ceiling fans and wide-open garage doors, there was little escape from the heat.

"A hot day like this, a car that comes in that's been running all day, it's like sticking your head in a furnace," Calandro said.

In New Jersey, soaring temperatures were suspected in a huge fish kill at a Piscataway lake, and beachgoers were on the sand and in the water before most people had arrived at work.

Diana Tredennick of East Brunswick, N.J., slathered herself with sunscreen before 8:30 a.m. "I'll be in the water a lot," promised Tredennick, who brought along a cooler filled with ice and water.

Some people had no choice but to muddle through the day at work. Lee Spivey, 42, stood on a street near ground zero, directing tourist traffic and moving construction trucks through lower Manhattan.

"You just deal with it," he said. "This is not the hottest day, but tomorrow might be."

The Associated Press contributed to this report.