Heat wave continues in the Bay Area
A high-pressure heat dome that has sent temperatures skyrocketing along most of the western United States was expected to start showing cracks Thursday, even as the Bay Area suffered through the hottest day of a heat wave that could send records tumbling.
“A lot of places could see new records by the time the day is over,” National Weather Service meteorologist Drew Peterson said. “It’s what we anticipated.”
At 12:30 p.m. Thursday, it was 103 in Concord, 100 on the Stanford campus and 97 in Gilroy. Temperatures in Eastern Contra Costa County, the Bay Area’s hottest spot, were expected to reach 110 on Thursday. It also was 100 degrees in Livermore, where the forecast high was 106. Morgan Hill, which was expected to get to 101, was at 94 degrees.
On the Monterey Peninsula, temperatures remained relatively mild as of midday Thursday. It reached 72 degrees at the Monterey Airport by 1 p.m. The Salinas Airport climbed to 84 degrees by 11 a.m. but cooled down to the high 70s by 1 p.m. Big Sur reached 92 degrees by noontime.
In San Jose, where the forecast high of 98 degrees would be 1 degree shy of a mark set in 1965, the mercury read 92 degrees at 12:30 p.m.
The excessive heat warning came because overnight temperatures remained warmer than usual throughout the region, with lows in the far inland areas dipping only into the low 60s. The warning replaced an advisory in effect since Wednesday and stays in place until 11 p.m. Friday.
The California Independent System Operator, which oversees the state’s electric grid, called for a statewide Flex Alert from 5 p.m. to 10 p.m. to reduce the risk of rotating blackouts when electricity demand soars.
Residents were asked to keep their thermostats at 78 degrees and delay using appliances such as washers, dryers and dishwashers.
An on-shore breeze coming from the ocean will remain “breezy to gusty,” Peterson said, and cities closer to the coast will be cooler. The temperature is expected to rise to 85 degrees in Oakland, with coastal areas remaining cooler. At 12:30 p.m., it was 82 in San Francisco, already exceeding the forecast high of 75.
The conditions that are allowing the heat to sizzle also are causing pollutants including smoke from fires in Arizona to become trapped low in the atmosphere. The Bay Area Air Quality Management issued a Spare the Air Alert Thursday and Friday.
“With hot temperatures and more cars on Bay Area roads, air quality is again expected to be unhealthy on Friday as more employees return to their workplaces and traffic steadily increases,” said Jack Broadbent, executive officer of the air district. “Rather than getting back in your car, consider working remotely, taking transit, biking or walking to improve our air quality and help us all breathe easier.”
The searing heat wave was ex
pected to send temperatures in the Central Valley up to 110 degrees Thursday, and near 120 in Las Vegas and Phoenix. It came as a severe drought across the West continues to worsen. Overall, 85% of California is now in “extreme drought,” up from 2% a year ago, according to the U.S. Drought Monitor, a weekly report issued every Thursday by the U.S. Department of Agriculture, NOAA and the University of Nebraska.
The only category more severe is “exceptional drought.” Statewide, 33% of California is now in that status — the most since March 2016 during California’s historic 201216 drought. Areas in exceptional drought include the East Bay, Marin, Sonoma, Napa and Solano counties, the Sacramento Valley from Sacramento to Redding, and the Southern Sierra.
Heat waves and droughts are not uncommon across California and the West. They have occurred for centuries. But climate change is making them worse.
The Earth’s average global surface temperature has risen 2.16 degrees Fahrenheit since the late 19th century, largely due to climate change from the burning of fossil fuels. Perhaps most noteworthy: The seven hottest years since 1880, when modern temperature records began, all have occurred since 2014, according to NASA.
“We expect more heat waves in a warmer climate,” said biologist Chris Field, director of the Woods Institute for the Environment at Stanford University. “For more than 30 years, many lines of evidence have pointed to the strong link between a warming climate and heat waves that are hotter, more frequent, and longer.”
By midday, temperatures surpassed 100 degrees in Danville, but Rachel Lantz, an employee of a community pool in the city, said there was no rush from the public to get in the water.
“The staff are hot, but we can get in the pool, so it’s not too bad,” she said.
She’s 20, and said of the heat, “This is just the way things are going to be.”
As expected, the region also sizzled on Wednesday, but no records were broken. Temperatures peaked at 98 degrees in Concord and Gilroy, 96 in Santa Rosa, 95 in Napa, 94 in Redwood City, 89 in San Jose, 87 in Oakland and 75 in San Francisco, according to the weather service.
Along the Central Coast, Monterey hit 73 degrees Wednesday, while Big Sur topped out at 98, King City reached a high of 97 and Santa Cruz was 98 degrees.
Relief from the heat will begin Friday, Peterson said. The heat dome is beginning to migrate away from the Four Corners Monument area, where Colorado, New Mexico, Arizona and Utah converge, Peterson said. As it does, it will lose its intensity, and pressure will begin to fall.
“It’s still going to be very warm, especially inland” on Friday and Saturday, Peterson said. “At the same time, you will see a difference of 5-8 degrees cooler each day.”
Another threat, according to Peterson, is dry lightning, which could develop in the southern Sierra Nevada. Dry lightning was responsible for igniting about 650 wildfires throughout the state last August.
Bay Area News Group reporter Kate Selig contributed to this story.