NEW YORK (CBSNewYork/AP) — It was another record-breaking scorcher on Saturday. Highs were at or near 100 degrees in New York City, a temperature not felt on July 23 in two decades.

Temperatures were near or just above 100 degrees in New Jersey by early Saturday afternoon, with heat indexes ranging from 105 to 110 degrees.

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The hottest spot was Atlantic City, which was at 102 degrees by mid-afternoon, while 101-degree readings were reported in Newark and Trenton.

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Lauren Nash, a meteorologist with the National Weather Service, said cities are experiencing the “urban heat island” effect.

PHOTO GALLERY: Heat Wave Hits Tri-State

“All the concrete and the black top warms up faster, so it keeps the city hotter and it stays hotter longer,” she said. Overnight temperatures did not get below 80 in some areas.

New York Deputy Mayor Stephen Goldsmith said, “The danger isn’t just the heat, it’s also the heat underground. Much of our infrastructure is below ground.”

To help New Yorkers beat the heat, city swimming pools have extended hours today. All 54 city pools will be open until 8 p.m.

The spray showers on city playgrounds will stay open until 9 p.m. Cooling centers across the city will also be open all day and many will have extended evening hours.

Officials are urging residents to stay indoors in air-conditioned areas and drink plenty of water.

Emergency room doctors say three to four days into an extreme heat event is when they start to see people overcome by the oppressive weather.

WCBS 880’s Sean Adams reports: Emergency Rooms On Alert

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“Heatstroke and dehydration can take you by surprise. Seniors, young children and those with high blood pressure, heart disease or lung conditions should be especially careful,” said Karen Halpfinger with the Westchester Health Department.

Most of us will muddle through this heat wave just fine, but some people are more vulnerable and slip through the cracks and that is why officials repeat the same warnings over and over, because lives are at stake.

“Check on their friends, family. If you’re family lives in another borough, they live in a county in a town across, give them a call, see how they’re doing,” said Dennis Mcholsky with state emergency services.

While temperatures might be slightly down from Friday, that doesn’t mean much. The Tri-state area hit triple digits in many areas including the beach.

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“We have been out here for a half an hour and it is ridiculous,” said one beachgoer at Jones Beach. “We are going to throw ourselves in the deep end to cool off.”

WCBS 880’s Kelly Waldron reports: Trying To Escape The Heat

Friday’s oppressive heat also left thousands of customers without power Friday night and Saturday in New York City, Westchester, Long Island, New Jersey and Connecticut.

National Weather Service meteorologist Joe Pollina says the heat will begin to ease Sunday. By Monday, it should be back in the 80s.

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