The San Francisco Bay Area baked under a warm dome of air on Thursday and the heat is expected to intensify Friday, bringing the potential for poor air quality and electrical outages, the National Weather Service said.
Friday is predicted to be the hottest day of the week with inland areas soaring into the mid-90s and low 100s this afternoon. Locations on the coast and along the bay are forecast to be in the high 70s to mid-80s.
The warm weather comes with high pressure building over California. “Whenever you have high pressure it means air is sinking toward the ground and it warms as it does that,” said Brooke Bingaman, a forecaster with the weather service said. “It creates that dome of hot air.”
The weather service issued a heat advisory for Friday across interior portions of the North Bay, East Bay, South Bay, Santa Cruz Mountains and interior Central Coast. An excessive heat warning will be in effect for Solano County on Friday.
The Bay Area Air Quality Management District issued a Spare the Air alert for Friday with air quality expected to diminish. The agency is asking the public to avoid driving to help prevent unhealthy smog accumulation.
PG&E spokesperson Tamar Sarkissian said the public utility is prepared for the heat with crews available to work around the clock if any heat related outages occur. PG&E is not planning a power shutoff as the risk for wildfires isn’t expected to be high with this event.
Heat-related outages occur most often due to transformer failure. Transformers, which help distribute power to homes and businesses, need periods of time to cool down, and that usually happens overnight, when temperatures drop, Sarkissian explained in an email.
“When we have unusual heat events with sustained high overnight temperatures, transformers are unable to cool down,” she said. “That puts stress on the transformer’s components, and they can become fatigued and can fail.”
The Bay Area will start to cool on Saturday.”The sea breeze is going to pick up so that will help cool us off,” Bingaman said. “Interior areas will still have some 90s but it won’t be as hot with low-to-mid-90s.”
Sunday marks a more significant decline in temperatures as a low pressure system pushes into Northern California. The interior will be 15 to 20 degrees cooler compared to the peak heating on Friday. There’s a small chance for very light rain in the North Bay on Sunday.