Kentfield hits 108 degrees in record-breaking heat

Kentfield hit a record temperature of 108 degrees on Sunday as a heat wave stifled the region and brought the threat of more rolling power outages.

The previous record for Sept. 6 in Kentfield was in 1923, when the temperature reached 104 degrees, according to the National Weather Service. The records go back to 1909.

The heat also tied Kentfield’s all-time record for the month of September, the weather service said. It was also 108 degrees on Sept. 2, 2017.

The exceptionally hot weather arrived as firefighters continued to battle the Woodward wildfire in the Point Reyes National Seashore and other blazes around the region. The Woodward fire, which started after a lightning strike on Aug. 18, was 95% contained at 4,835 acres as of Sunday evening, according to federal firefighters.

Elsewhere Sunday, downtown San Francisco hit 100 degrees by 3 p.m., unofficially smashing the old record of 92 degrees set in 1904, according to the National Weather Service. Livermore reached 108 degrees, Oakland 99 and San Jose 102 — all unofficial records.

The heat triggered a “flex alert” from Cal ISO, the state’s energy grid managers, warning that rolling blackouts could be necessary if power demand — fueled largely by air conditioners switching on up and down the state — exceeded supply. As many as 2.3 million customers were scheduled for outages starting Sunday evening if consumers didn’t quickly reduce demand.

Rolling blackouts were avoided Saturday evening after Cal ISO called a “stage 2” alert, warning that such outages were imminent if consumers didn’t reduce their energy usage. Regulators say that residents should set their air conditioning to 78 degrees or higher, avoid using large appliances and turn off unnecessary lights to save energy.

At the same time, the stagnant, hot air was continuing the region’s run of dirty skies, with smoke from wildfires pressed down into the Bay Area by the high-pressure system. Air-quality readings across the Bay reached from moderate to unhealthy on Sunday, and a “spare the air” alert in effect since Aug. 18 was extended through Monday.

National Weather Service meteorologist Duane Dykema said coastal areas were likely to see only slight cooling on Monday.

“You won’t have to go very far from the ocean to get hot temperatures,” Dykema said. “We’re not going to see enough cooling tomorrow that others will even notice.”

Forecasters still expect heat to give way to gradual cooling after Tuesday, but they remained on guard. Late Sunday afternoon, the weather service officially declared a “red flag warning” for Monday evening through Wednesday morning, with gusty off-shore winds feeding hazardous fire conditions, lowering humidity levels even further and possibly spreading smoky air from inland.

Firefighters continued battling the three major wildfire complexes feeding that smoke into the atmosphere, all three sparked by dry lightning strikes during the August heat wave. As of Sunday evening, the SCU Lightning Complex, a series of fires burning in locations in Santa Clara, Alameda, Contra Costa, San Joaquin, Merced and Stanislaus counties, was 88 percent contained at more than 396,000 acres, making it the second-largest wildfire in recorded state history.

The LNU Lightning Complex, burning in Sonoma, Lake and Napa counties was about 91 percent contained at more than 375,000 acres, the third-largest wildfire in state history.

The CZU Lightning Complex that ravaged the Santa Cruz mountains along the Santa Cruz and San Mateo coasts was about 68 percent contained, with more than 86,000 acres consumed.

CalFire said on Sunday that more than 2 million acres had burned in California since Jan. 1, a record since the agency began gathering such information in 1987.

Dykema, the meteorologist said residents need to be especially careful about the cumulative effects of the weather and smoke.

“This is our third consecutive day of heat,” he said. “With heat events like this on multiple days, each successive day can cause more stress on the human body, with potential health impacts.”

Bill Patzert, a retired climatologist from the Jet Propulsion Laboratory, said August is usually the hottest average month for most of California, but September “is the heat wave month.”

Patzert said the current condition is similar to what the state sees in October, November and December when offshore winds from the desert blow hot air to the coastline.

The weekend’s weather could be traced to a high-pressure system in the North Pacific that has parked over the Great Basin in western Utah and Nevada, Patzert said.

“High-pressure systems are dominating all the way from Seattle to San Diego,” Patzert said. “Get out the record book.”

The Marin Independent Journal contributed to this report.