High Temperatures, Humidity to Bake Bay Area Through Next Week

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Pedestrians walk by signs for bay cruises at the temporarily closed Red and White fleet on Aug. 13, 2020, in San Francisco.  (Justin Sullivan/Getty Images)

A long heat wave is settling in across most of California, threatening wildfires and raising public health risks that include the spread of COVID-19 over the next week.

It's not a dry heat, either. Temperatures will feel worse than usual, especially overnight, as a result of an unusual boost in atmospheric humidity caused by the remnants of a hurricane.

On Friday, high temperatures around the Bay Area included 109 in Fairfield, 103 in Petaluma and 103 in Santa Rosa, according to the National Weather Service.

Climatologist Daniel Swain says some coastal areas will escape the most unbearable temperatures, but that heat will blanket 90% of California's land mass, so most people should get ready.

“I suspect this event will probably end up being one of the most significant widespread California extreme heat events in the past decade, if not longer,” writes Swain on his Weather West blog.


The National Weather Service has issued an excessive heat warning in effect through next Wednesday, noting that “drastic temperature differences will exist” between the coast and further inland, raising fears that Californians will flock to coastal areas despite the pandemic.

Cal Fire has issued a red flag warning for the Sierra foothills and parts of northeastern California through next week.

However, that won’t necessarily prompt a public safety power shutdown. A spokeswoman for PG&E says the utility’s in-house meteorologists take other factors into consideration, and the utility does not forsee issuing a PSPS this weekend.

County emergency and health officials are offering air conditioning at cooling centers for residents seeking a respite from the heat. Everyone will have to wear a mask and observe social distancing requirements, and capacity will be reduced to comply with health orders. People who believe they might have been exposed to COVID-19 should stay home.

In Santa Clara County, the Office of Emergency Management has opened cooling centers, some of which will be available until 9 p.m. over the weekend. Contra Costa has opened cooling centers at community centers where the coronavirus has curtailed the usual programs and services. Solano County cooling centers are usually in libraries; since they’re closed on weekends, few options remain, including at community centers in Fairfield. The county recommends calling first.

You can use NOAA’s experimental tool to see more about your heat risk over the next week.

Health officials advise drinking water, keeping children and pets away from heat whenever possible, and checking on older neighbors, especially if they are alone.