Residents of western U.S. states awoke on Monday to more scorching heat that was expected to break record highs and grip the region through the early part of the holiday week, meteorologists said.
Temperatures were likely to hit well over 100 degrees Fahrenheit (38 degrees Centigrade) in Fresno, California, Phoenix and to the north in Boise, Idaho, and Spokane, Washington, according to Accuweather.com.
Temperatures in western states are 10 to 20 degrees above average, according to the National Weather Service.
"Many of the same locations that broke records over the weekend may break them again on Monday," it said on its web site.
The blasting heat was expected to last at least through Tuesday, meteorologists said.
"While many folks over the interior West are accustomed to and expect hot weather during the summer, this pattern is taking the heat to the extreme," said AccuWeather meteorologist Alex Sosnowski.
In Death Valley, California, the mercury hit 128 degrees F (53 degrees C) on Saturday and Sunday, tying the June record, meteorologists said. The highest temperature recorded on earth was 134 degrees F (57 degrees C) in Death Valley in 1913.
In the eastern United States, meanwhile, low heavy cloud cover and the threat of thunderstorms were causing flight delays at airports in the New York City region and in Philadelphia.
Dry drought conditions and concern over the risk of fires were forcing the cancellation of Fourth of July fireworks celebrations, particularly in Colorado, Utah, Arizona and New Mexico, according to Accuweather.com.
The heat wave, caused by a dome of hot air trapped by a high pressure ridge, contributed to the death of an elderly man on Saturday in Las Vegas, where searing temperatures reached an all-time high of 118 F (48 C) and sent scores of people to hospitals with heat-related illnesses.
(Reporting and writing by Ellen Wulfhorst)