Edward Butcher, 64, tries to keep cool at his window in Queens
A heat emergency is in place in New York City, as high temperatures grip the east of the United States for a second day.
Mayor Michael Bloomberg has urged residents to conserve energy to avoid the blackouts experienced last month.
Across the city, 383 "cooling centres" have been opened, and public pools opened for extended hours.
The heatwave, which has been moving across the US from California, is also affecting Philadelphia and Washington.
Temperatures have cooled in California, where the record 15-day heat wave was blamed for 136 deaths and widespread power cuts.
Dodging the heat
Philadelphia, New York City and Washington DC saw maximum temperatures of 38C (100F) on Wednesday.
Similar temperatures are predicted for Thursday after which they will drop to mid-30C.
New York City has not seen such a string of hot temperatures since July 1999.
Lights on the Brooklyn Bridge and the Empire State Building were dimmed to save power as office workers stayed at their air-conditioned desks.
National Weather Service meteorologist Dennis Feltgen said the temperatures were "extremely dangerous".
"You can't be outside in that kind of heat without taking precautions," he was quoted as saying by Reuters news agency.
On the New York subway, there was no air conditioning on three carriages of the train passenger Sayed Bukhari took into Manhattan.
"People were crying," he told the Associated Press.
New York street trader Victor Francese, 66, told Reuters he had been trying to stay cool by "running in and out" of nearby air-conditioned buildings.
The use of lifts in New York has been reduced in city administration buildings in a bid to conserve energy and major private companies have also announced conservation measures.
The mayor's office has issued guidelines for the use of air-conditioning in homes, urging people not to leave it on when not at home.
Last month, thousands of people in the New York borough of Queens endured high temperatures with no electricity, after distribution cables failed.
Customers in the Washington area are reportedly on their way to setting a new record for electricity demand.
But power grid operators have said they believe they can meet the increased demand for electricity.