Sweltering heat continues its grip in California, stressing the power grid and pushing Death Valley to near-record temperatures -- with relief still several days away.
Utility companies urged residents to conserve power, saying that it was struggling to keep up with the demands of air conditioners.
"What happens is that we get into a fatigue factor" after four days of scorching heat, said Stephanie McCorkle, spokeswoman for the California Independent System Operator, which took the unusual step of issuing a seven-hour-long "Flex Alert" on Monday. It was the summer's first alert.
"Consumers get tired of keeping thermostats at 78 degrees," she said. "And there's a lot of wear and tear on power plants."
There were no heat-related deaths in the state, although Santa Clara County emergency rooms reported visits by people with illnesses caused by the heat, according to Tina Walker of the California Office of Emergency Services. On Sunday afternoon, two women drowned while swimming at Boony Doon Beach, west of Santa Cruz.
Temperatures soared to 114 degrees at Pinnacles National Park, southeast of San Jose. Some campers sought refuge in the air-conditioned Visitor's Center, while others packed up and left.
"A few folks came in and bought a Monopoly set and just stayed here inside, where it is cool," said Pinnacles ranger Carlo Arreglo. The park's famed condors may perch -- or head to the coast, he said.
Death Valley National Park, the hottest place in America, cooled down from Sunday's 129 degrees -- to 127 on Monday, according to the National Weather Service. It was the first time since 1998 the valley had baked in temperatures 127 or higher for three days in a row, said Bob Benjamin, a weather service meteorologist.
It was cooler still in Livermore -- 103 -- but no one noticed. "We're shut down -- done by noon," said roofer Greg Lukinbeal, owner of Heritage Roofing. With roof temperatures averaging 10 degrees warmer than the air and roofers required to wear heavy clothing to prevent injury, "it's not worth staying up there," he said.
A smothering dome of high pressure, centered in Arizona, is creating the heat, said Jan Null of Golden Gate Weather Service.
And because the heat hasn't dropped precipitously at night, as it usually does, it is easy for daytime temperatures to soar, he said.
Lightning was blamed for an Arizona fire that killed 19 members of an elite wildland firefighting unit Sunday. The dead included three California natives: Kevin Woyjeck, of Seal Beach, and Hemet natives Billy Warneke and Chris MacKenzie. Members of the Granite Mountain Interagency Hotshot Crew died as the evacuated town of Yarnell, Ariz., was ravaged by the blaze. It was the worst firefighting tragedy in the U.S. since 1933.
It was so hot in Phoenix over the weekend that 18 US Airways regional planes were grounded. While large aircraft like the Airbus can fly in 127 degrees, smaller aircraft are restricted to 118 degrees because their engines don't provide as much thrust, reducing lift on the wings, said US Airways spokesman Todd Lehmacher.
The mercury plunged to the low 60s on Monday along a narrow fringe of coastal California. It was sweater weather on the fairways of Pebble Beach. In Pescadero, olallieberry pickers at Phipps Country Farm reveled in the brisk ocean breeze.
"Escape to the heat, or escape to the cool. We have both -- a 40 degree difference over 40 miles," said Null.
By comparison, the temperature across the 400-mile length of Kansas varied one degree.
By Tuesday night, a little fog along on the coast will begin to help cool down the days, Null said.
Staff writer Dana Hull and The Associated Press contributed to this article.
Contact Lisa M. Krieger at 650-492-4098.