NEW YORK (AP) – With people across the nation taking refuge in air-conditioned spaces and precious shady spots, New Yorkers continued to swelter in a broiling heat wave for a second day Tuesday, one that prompted officials to open cooling centers for residents.

“The city is one big oven today,” said Juliana Brugger, 35, a Brooklyn resident wearing a business suit and heels. “I feel soaked with sweat, my ankles are swollen from the shoes, and I just walked one block to get lunch.”

On the streets of New York, shade competed with parking spaces as valuable commodities. People made their way under narrow awnings, lounged under trees and took breaks beneath the umbrellas of hot dog stands. City pool hours were extended for a second day until 8 p.m.

The thermometer hit 92 degrees by noon in Central Park, with a predicted high around 97, the National Weather Service said. The heat index, which measures the combined effects of heat and humidity, was expected to reach 104 degrees around the city.

Subway lines were out for about an hour on the city’s west side. Transit spokesman Charles Seaton said he wasn’t sure if the outage was weather related, “but it’s sure causing headaches.”

The heat may have caused a subway train to lose power Monday, stranding commuters for more than two hours. About 70 people had to be evacuated. Seaton said the power loss may have been caused when the third rail, which powers the train, buckled.

Fierce heat blanketed the nation from the southern Plains to the Northeast, and scores of communities reported temperatures of more than 100. Parts of Kansas and Oklahoma hit 108, and temperatures in some areas were likely to exceed 105 through the middle of the week. In the southeastern Colorado town of Lamar, the temperature hit 100 in the fourth straight day of triple-digit readings in the state.

The heat prompted calls for electricity conservation and pushed electricity consumption to a record in some states. The Long Island Power Authority said Monday it broke the record for demand set during last summer’s three-day heat wave.

In New York City’s Central Park, the temperature record for the date, set in 1953 at 100 degrees, remained unbroken Tuesday.

Consolidated Edison spokesman Chris Olert said equipment problems, possibly heat related, kept the power out for about 3,600 customers in Westchester County, 180 in Queens and about 580 in the Bronx. On Monday as much as 17,000 customers were without power.

Residents were urged to conserve electricity and water, and the city opened three cooling centers.

“There’s no supply problem,” Olert said. “We spent a billion dollars to get ready for this summer, but the cables are still sometimes vulnerable in the heat.”

Power problems persisted at LaGuardia Airport, where a Con Edison feeder cable was being repaired Tuesday. The problem was affecting the terminal for American Airlines and the Delta Shuttle.

Delta canceled at least two flights and American Airlines canceled some of its flights through 2 p.m. Tuesday, said Port Authority of New York and New Jersey spokesman Pasquale DiFulco. Power was off at the Marine Air Terminal, where the Delta Shuttle departs, but there were no major delays. The power outage began at 8:30 p.m. It was expected to be fixed Tuesday afternoon.

On Monday, Con Ed worker Lou Velez had been outside since 7 a.m. with two others working on power lines as more and more customers flicked on their air conditioners.

“It’s even hotter down there than it is up here,” he said, taking off his blue hard hat and wiping the sweat dripping down his face. “We’re working all day to make sure everyone else stays cool. It kind of stinks, but someone has to do it.”

The Northeast experienced some of the nation’s highest temperatures Monday. In New Jersey, for example, readings of 102 in Union and 101 in Logan had been record by 4 p.m.

The federal government reported last week that the first half of 2006 was the warmest in the United States since record keeping began in 1895. The average temperature for the 48 contiguous states from January through June was 51.8 degrees, or 3.4 degrees above average for the 20th century.