What’s behind the plunging temperatures? It’s called a heat dome: an atmospheric cap traps warm air over the western US, causing intense heat. You can read more here about the science behind California’s worsening heat wave, as explained by the Chronicle’s weather science team.
Our reporters are out and about today to bring you the latest news from the Bay Area.
Latest updates:
The emergency of the power grid intensifies
Thousands of Bay Area residents lose power as heat batters transformers
Record heat in the Bay Area caused “unplanned heat-related outages” for 22,418 customers as of 6 p.m. Monday, according to a PG&E spokesman. The main problem was transformer outages – transformers need time to cool down and usually do so overnight when temperatures drop. But during a heatwave temperatures are still high after dark and transformers can fail. It is more common in coastal areas than inland, where temperatures are typical and transformers are built to handle more heat. These outages were not state-ordered rolling outages, which are due to a statewide power shortage and have not occurred since 6:40 p.m. Monday, nor are they public safety outages to prevent forest fires.
California grid moves to higher emergency alert level
From 6:30 to 9:00 p.m., California’s grid will move to Energy Emergency Alert Level 2, the highest emergency level so far in this heat wave. If the grid goes through emergency alert level 3, it will turn into rolling blackouts as demand outstrips supply.
The Bay Area School District is cutting back hours at three schools
The Novato Unified School District will operate a reduced schedule at Lu Sutton Elementary School, Novato Middle School and Hill Elementary School, schools that have limited or no air conditioning, during the county’s excessive heat advisory from Marin from Tuesday to Friday. At the high school, each period will be shortened and the school day will end at 1:15 p.m.
Preliminary heat records were broken in the Bay Area
Preliminary high temperatures for the Bay Area’s scorching heat wave are coming in, with early reports showing Livermore possibly soaring to 113 to 116 degrees, which would break its daily record high of 108 degrees that was set in 1950. Buchanan Field Airport in Concord tied its all-time record of 112 degrees from 2020, while downtown Oakland reached 100 degrees, breaking its daily record of 95 degrees in 2008.
San Francisco Airport tied its daily record high of 93 degrees as of 2020. A high of 102 degrees was recorded at both San Jose International Airport and Mountain View, breaking the previous daily record highs of 99 and 97 degrees in 2009, respectively. Palo Alto reached 98 degrees, breaking the 2008 daily record of 95 degrees.
Sonoma County Airport Station reached a high of 111 degrees, breaking the daily record of 109 degrees set two years ago. Napa County Airport reached 109 degrees, breaking the record of 106 degrees in 2020. The National Weather Service Bay Area office will begin verifying records Monday afternoon, but it’s unclear when a final report will come out .
Fairfield’s already record-setting temperatures could rise even further on Tuesday
Fairfield, in the Travis AFB area, preliminarily recorded a high of 116 degrees, an all-time high for the Bay Area. Temperatures in the city could rise further on Tuesday, according to Chronicle meteorologist Gerry Diaz. Livermore was another city that saw unbearable temperatures on Tuesday.
The California grid declares the first phase of emergency on Tuesday
Even as the grid headed toward a power shortage on Monday, officials preemptively declared another emergency on Tuesday from 5 to 9 p.m. Power demand is expected to reach its highest levels ever on Tuesday, causing the specter of blackouts to linger in California.
A bank sign says 106 degrees at 4:25 p.m. on 4th Street in San Rafael, Calif., Monday, Sept. 5, 2022. Scott Strazzante/The Chronicle
Fairfield records hottest temperature in Bay Area history
Fairfield reached 116 degrees late Monday afternoon, which, assuming the National Weather Service finalizes the number, would be the highest temperature ever recorded in the nine-county Bay Area, according to the meteorologist at Chronicle Gerry Diaz. The weather service will begin verifying records Monday afternoon. The number was recorded in the vicinity of Travis Air Force Base.
Flex Alert goes into effect at 4 p.m
California’s grid operator’s request for Californians to reduce their electricity use, a request known as a Flex Alert, is now in effect. Californians are asked to refrain from using energy-guzzling appliances such as dryers and dishwashers, turn off unnecessary lights and keep air conditioning at or above 78 degrees (85 for those not at home). The aim is to avoid blackouts, which could happen if the grid is overloaded by electricity loads. Regulators have said Monday will be the grid’s toughest day yet during this heat wave.
A young woman tries to stay cool in the stands at the Highland Games in Pleasanton on Sunday. Monday is expected to be even hotter.
Brittany Hosea-Small/Brittany Hosea-Small / Special to The Chronicle
Chance of storms next weekend
Tropical Storm Kay is spinning off the southern coast of Baja California Sur, and is expected to become a hurricane by the middle of the week. Its remnants will bring plenty of moisture to Southern California. That moisture will help spawn scattered wet thunderstorms from San Diego to Santa Barbara, along with parts of Kern County and the Mojave, according to Chronicle meteorologist Gerry Diaz. The latest weather models indicate that some of this residual moisture will also make it to NorCal next weekend. If it moves enough, Northern California could also see wet storms. But if only sprinkles of residual moisture come in, the possibility of these storms producing dry lightning in the heat-stressed forests of Northern California next weekend can’t be ruled out.
Parts of the Bay Area see power outages
Up to 5,000 homes and businesses were without power in Napa County, as well as more than 5,000 in an area west of Vacaville, according to a PG&E outage map. The company could not immediately be reached for an explanation, but the extreme heat is known to strain all infrastructure, including electrical equipment. The outages are not part of the statewide blackouts that are a possibility, though not inevitable, for Monday afternoon and evening.
California regulators are keeping an eye on outdoor labor violations
Cal/OSHA has told businesses in the construction, agriculture, tree trimming, landscaping, car wash and warehouse fields that it plans to conduct “targeted inspections” to ensure worker safety during the heat wave By law, employers must provide fresh water, access to shade and regular breaks, and closely monitor employees for signs of heat illness in extreme temperatures.
Construction worker Gabriel Caballero drinks water while working on Fitzuren Road as temperatures rise in Antioquia, Calif., Thursday, Sept. 1, 2022. Jessica Christian/The Chronicle
“Blackouts are a possibility today,” says the network boss
The near-unprecedented strain on the power grid will peak Monday and Tuesday, and grid officials will look for every possible way to avoid blackouts. The best thing Californians can do, they say, is to reduce electricity use from 4 to 10 p.m. Monday night (and similar hours this week), to offset the immense power demand from air conditioners . Read more here about how the public can help prevent blackouts.
The Sacramento Valley was expected to see record highs of up to 119 degrees
The heat wave in the Sacramento Valley is reaching its peak today and tomorrow, meaning it’s poised to experience some of the hottest temperatures seen in the continental United States this year. Weather models project highs today reaching 115-119 degrees, according to Chronicle meteorologist Gerry Diaz. Sacramento, Modesto and other cities are expected to break their all-time records in the coming days. Little relief from the heat is expected overnight, with overnight temperatures staying in the 70s, while some of the peaks along the Sierra and Diablo ranges will likely stay in the 80s overnight. Temperatures will finally drop below 110 degrees in most of the valley by Thursday, but the weather will still be 100 to 105 degrees Thursday through Saturday.
Some BART trains are running slower due to the heat:
“There is a 10-minute delay on the Antioch Line in the Antioch and SFO directions due to warm weather conditions,” BART said on its alert channel. The service had also slowed trains on Sunday for the same reason.
110 degree temperatures reaching Wine Country and East Bay
Chronicle meteorologist Gerry Diaz reports here on which Bay Area cities are likely to hit 110 on Labor Day.
A person runs in the midday rays at Lake Merritt in Oakland on Monday. Heat advisories and advisories have been extended through Thursday.
Santiago Mejía/The Chronicle
Don’t go to Stinson Beach, Marin officials warn
“If you’re not already…