Residents of western U.S. states awoke on Monday to more scorching heat expected to break record highs and grip the region through much of the holiday week, meteorologists said.
A wildfire fueled by the record heat and high winds killed 19 people, including at least 18 elite firefighters in Arizona, the biggest loss of life battling a U.S. wildland blaze in 80 years, officials said.
The crew from the Prescott, Arizona, Fire Department was killed on Sunday when the fast-moving blaze trapped them near Yarnell, a town about 80 miles northwest of Phoenix.
Temperatures were likely to hit well over 100 degrees Fahrenheit in Fresno, Calif., Phoenix and to the north in Boise, Idaho, and Spokane, Wash., according to Accuweather.com.
"A large area of high pressure will continue to bring dangerously high temperatures to much of the western U.S. on Monday and into the middle of the week," the National Weather Service said. "Triple-digit temperatures will be common across the Southwest, but will also occur as far north as the northern Rockies and the Pacific Northwest."
A record high of 104 F was set in Boise on Sunday. Many locations that broke records over the weekend may break them again on Monday, the NWS said.
Temperatures in western states are 10 to 20 degrees above average, it 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.
California's power grid operator on Monday issued a rare plea for customers in the north of the state to conserve energy over the next few days.
The California ISO, which operates the grid in most of California and parts of Nevada, said it was anticipating a spike in air-conditioner usage would add to typical demand.
Temperatures in the Los Angeles metropolitan area were expected to hit 95 F on Monday, about 13 degrees above normal for this time of year, according to Accuweather.com.
In Death Valley, California, on Sunday, the temperature hit a record high for June at 129 F, the NWS said.
The highest temperature recorded on earth was 134 F in Death Valley on July 10, 1913.
"Excessive heat will continue through Independence Day as a strong ridge of high pressure holds over the western states," the NWS said in Las Vegas. "An excessive heat warning is in place for much of the area through Thursday evening for this intense and dangerous heat wave."
The heat caused an interstate highway ramp to buckle in Salt Lake City, state transportation officials said. The ramp was closed for about four hours on Saturday night before it was repaired, local media reported.
In the eastern United States, meanwhile, low heavy cloud cover, thunderstorms and heavy rains were causing flight delays at airports in the New York City region and in Philadelphia.
Due to thunderstorms, delays in departing flights at John F. Kennedy International Airport were as long as 90 minutes and increasing, the Federal Aviation Administration said.
Downpours prompted flash flood warnings to be issued for several locations in the New York City area.
The stream of tropical moisture stretching north along the East Coast was expected to deliver "daily, if not hourly, torrential downpours" in some areas, Accuweather said.
The storms were likely to keep battering the coast through Tuesday and then move westward and inland Wednesday through Friday to Mississippi, Tennessee, Kentucky and Ohio, it said.
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.
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 and sent scores of people to hospitals with heat-related illnesses.
© 2014 Thomson/Reuters. All rights reserved.