U.S. East Coast swelters under lingering heat wave

(Reuters) - A heat wave blanketing the northeastern United States is expected to move west after the Fourth of July, bringing dangerous temperatures as far as southern California, the National Weather Service (NWS) said on Tuesday.

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An excessive heat warning is in effect through Tuesday night, with heat index values – which combine temperature and humidity – in New York City reaching 106 degrees Fahrenheit (41°C).

A seven-day heat wave, which the NWS said occurs approximately once every 33 years, began in New York on Saturday. Parts of New England experienced record-setting temperatures over the weekend, said Dan Petersen, an NWS meteorologist.

At least one heat-related death has been reported since the heat wave began late last week - a Pennsylvania woman who died while working in her garden on Saturday. Another death, of an elderly man in Kansas City, was being investigated.

For the Fourth of July holiday, Petersen warned people celebrating outside to remain in the shade and drink plenty of fluids.

“Anyone outside in locations with expanded areas of heat is going to have to take precautions,” Petersen said. “This is the peak of summer – the hottest time of the year.”

The NWS also issued an air quality alert on Tuesday, warning of excessive pollution levels in the New York area into the evening hours.

But later this week, a storm front is expected to roll through and cool down the eastern seaboard for the weekend, Petersen said, providing relief to Washington, D.C. and Philadelphia on Friday night before heading down to the Carolinas.

In a reversal of normal patterns, Petersen said, the hot weather will head west, hitting the central United States late in the week before reaching Los Angeles and San Diego on Friday.

“The central part of the country is going to get hot and humid,” Petersen said. “In Southern California, the heat coming out of the deserts will expand and go into the valley areas.”

Reporting by Diana Kruzman; Editing by Marguerita Choy