A heat wave in the Bay Area has pushed temperatures 10 to 20 degrees above normal, prompting a heat advisory for the Bay Area and Central Coast that started Tuesday evening and that is expected to last through Thursday evening. A ridge of high pressure building in the southwest region of the U.S. is the cause of the heat wave.
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Joe Merchant, a meteorologist at the National Weather Service, told SFGATE the heat will be exacerbated by the plume of subtropical moisture that arrived in the Bay Area and that is linked to the remnants of Hurricane Marie, which drenched the Los Angeles area over the weekend.
"It's really just making things a little more humid, which does add to the impacts of heat risk," Merchant said. "We are feeling the moisture in the form of higher humidity, but we're not expecting any thunderstorms or anything like that from that moisture."
During the heat wave, parts of the East Bay are expected to reach triple digits, with Walnut Creek and Concord both forecast to hit 103 degrees, while San Francisco is expected to see temperatures near 90 degrees. In the North Bay, Santa Rosa is forecast to reach 96 degrees, while in the South Bay, temperatures are expected to reach 99 in San Jose.
The Bay Area Air District issued a Spare the Air alert for Wednesday due to ozone pollution that's forecast to hit unhealthy levels.
"High inland temperatures, combined with light surface winds and a delayed afternoon sea breeze, is expected to produce elevated concentrations of ozone, or smog," the alert said.
The weather pattern is causing dangerously hot conditions in Southern California, partially due to high humidity from Hurricane Marie that is making it more difficult for people to cool naturally. Humidity makes this week "much more dangerous" than previous heat waves, the weather service's forecast read. "All residents should limit your outdoor activities during the afternoon, seek air conditioned spaces, and take lots of breaks."
The humid weather also indicates that temperatures will likely remain relatively high overnight, giving people less time to cool down.
A historically strong El Niño in the Pacific Ocean means warmer water off the Southern California coast is contributing to the humidity. Additionally, El Niño brings higher than normal water temperatures, so tropical storms and hurricanes are possible in the coming months.
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This article originally published at Heat advisory issued for Bay Area as hurricane remnants bring muggy weather.