California’s worst heat wave has arrived for the final day of the Labor Day weekend celebrations, with temperatures expected to reach 110 degrees in St. Helena and Healdsburg. The intense heat has prompted warnings of possible blackouts in California’s power grid on Monday.
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 around the Bay Area, and our meteorologist is on hand to talk about what he’s seeing.
Latest updates:
Don’t go to Stinson Beach, Marin officials warn
“If you’re not in Stinson Beach yet…we suggest you don’t go,” the Marin County Sheriff tweeted Sunday. There are “hours of delays getting into the area, and parking lots and street parking are full.” On Sunday, the sheriff’s office said it had issued more than 145 citations in Stinson Beach. Visitors are asked not to block driveways or park in yards, and to be respectful of residents.
If you haven’t been to Stinson Beach yet… We suggest you don’t go.
Expect hour-long delays getting into the area, and parking lots and street parking are full. pic.twitter.com/1XMRE5qxPt
— Marin County Sheriff (@MarinSheriff) September 5, 2022
California lawmakers want to classify heat waves
On Gov. Gavin Newsom’s desk is AB2238, a bill that would direct the state Environmental Protection Agency to create a rating system for heat waves by 2025. Hurricanes, earthquakes and even atmospheric rivers are classified by their gravity, so why not heat waves? It’s unclear how the current heat wave would be classified, but officials say its extreme temperatures and long duration make it particularly dangerous. Learn more here about the heat wave classification bill, which passed unanimously with bipartisan support.
Parking lots at the Marin beaches and near the Golden Gate Bridge area are full
The Golden Gate National Recreation Area tweeted that parking lots at Stinson Beach, Muir Beach and Rodeo Beach in Marin County are full, as are most of its lots in San Francisco. “We welcome our visitors escaping the heat and remind them to be patient, stay shaded, and not take risks with cold ocean currents or coastal cliffs,” the park service tweeted.
Dozens of beachgoers flocked to the Bay Area coastline Saturday afternoon as temperatures began to rise ahead of a predicted heat wave that has state officials worried about heat-related illnesses and possible forest fires.
Greg Griffin/The Chronicle
Even San Francisco is already experiencing “extreme” heat.
Heat in San Francisco is considered extreme when it exceeds 85 degrees, and just before noon, the downtown reading was already 89 degrees. However, the city will remain cooler than most parts of the sweltering region and state.
The head of the California network says Tuesday’s demand is expected to be the highest ever
Amid scorching temperatures in California, the state’s electric grid operator is forecasting the highest power demand in the state’s history. Californians burned through 50,270 megawatts of power on July 24, 2006, but California Independent System Operator President and CEO Elliot Mainzer said at a news conference Monday that expected demand has exceeded the peak Tuesday’s history. He asked Californians to conserve power during the key hours of 4pm to 10pm this week and hoped those reductions and importing power from other states could see the state through Monday and Tuesday without blackouts .
California Grid issues a Stage 1 Emergency Warning
In a sign of the intense stress on power sources caused by the heat wave, the California grid operator has issued a notice of Energy Emergency Alert 1 for Monday, effective from 5 to 9 p.m. . This is the first level 1 emergency alert for the network. so far this heat wave, and is designed to reduce energy demand from large customers and create more supply. If the grid goes through emergency stages 2 and 3, which grid officials believe could happen on Monday, then it’s time to shut down because the demand, sent on a large scale by the use of air conditioning, exceeds the offer. Read more here about the near-unprecedented strain on California’s power grid.
Fire danger is high in California
Officials are warning against any activity that could start a fire, as the extreme temperatures have further dried out the vegetation and made it highly vulnerable to a spark. Fire danger is high through Friday for most of California.
How long will the heat wave last?
What seems like a never-ending heat wave peaks this Labor Day, with widespread temperatures of 105-110°F blanketing the North Bay, East Bay, and Sacramento Valley. Even San Francisco is suffering from some of the heat wave, with parts of the city climbing into the 80s today. This historic heat wave isn’t done with California yet. With the heat wave expected to continue, all excessive heat advisories and advisories for the Bay Area and Sacramento Valley have been extended until 8 p.m. Thursday.
Fans take advantage of the shade as they watch the San Francisco Giants play the Philadelphia Phillies at Oracle Park in San Francisco on Sunday.
Scott Strazzante/The Chronicle
A hiker suffering from heat exhaustion rescued from Montara mountain
Officials rescued a hiker who had experienced heat exhaustion on Montara Mountain in San Mateo County on Sunday, according to a tweet from Cal Fire’s CZU branch. Read here about officials’ warnings about outdoor exertion this weekend, following a string of high-profile heat-related deaths over the past year.
Coastside Fire Engine 44, @CAStateParks & @CHP rescued a hiker suffering from heat exhaustion Sunday from Montara Mountain. Waiting for more details… 🚁 pic.twitter.com/GNii2RztLS
— CAL FIRE CZU (@CALFIRECZU) September 5, 2022
Flexible alert in effect Monday from 4 to 10 p.m
During this time, utility officials are asking Californians to refrain from using energy-intensive appliances, such as dryers or dishwashers, and to turn off unnecessary lights. They’re also asking people to keep their air conditioning at 78 degrees or higher during this time (it’s a good idea to cool the house before 4 p.m.). This is the latest in a series of flexible alerts during the heatwave.
A bicyclist rides along Lake Merritt during the Labor Day weekend heat wave in Oakland.
Michaela Vatcheva/Special to The Chronicle
Possibility of blackouts on Monday
Power grid conditions are expected to deteriorate late Monday afternoon as air conditioners work overtime and demand for electricity increases. Grid officials anticipate emergency conditions and will ask consumers and businesses to conserve energy from 4 to 10 p.m. to avoid blackouts. Read more here about why network officials are so concerned.
What is a heat wave?
Heat waves are usually defined as unusually hot weather lasting more than two days. But what is considered unusual can vary between different geographic regions of California. For example, a high temperature of 95 degrees Fahrenheit might describe a typical summer day in the Central Valley. But those temperatures could be unbearable in San Francisco, where residents typically don’t have air conditioning. Weather experts take these differences into account when issuing extreme heat warnings. Go here to read more about the science of heat waves.