Pacific Gas and Electric Co. (PG&E) has warned of potential public safety power shutoffs this week as a combination of high heat, low humidity, and strong offshore winds creates critical fire weather conditions across Northern California, including Sonoma, Napa, and other counties.
The National Weather Service (NWS) has issued a Red Flag Warning for the East Bay Hills and North Bay Interior Mountains, effective from 11 p.m. Wednesday until 9 a.m.
Thursday, due to gusty winds expected to reach 35 to 40 mph, with ridge tops possibly seeing gusts over 60 mph. Humidity levels are forecast to drop to between 10% and 20%, making vegetation extremely dry and susceptible to rapid fire spread.
Temperatures on Thursday are expected to soar into the high 90s, potentially reaching 100 degrees in far inland areas of Contra Costa and Alameda counties, as well as in the Santa Clara Valley and Eastern Hills. The North Bay, including Napa and Santa Rosa, is also forecast to hit at least 97 degrees.
The NWS has issued a heat advisory from noon Thursday to 11 p.m. Friday, warning that the heat could affect sensitive individuals, especially those without adequate cooling or hydration, and may impact health systems and heat-sensitive industries.
A brief respite came Wednesday with slightly cooler temperatures, but the heat will intensify Thursday before a dramatic cooldown arrives over the weekend. NWS meteorologist Lamont Bain explained that an offshore jetstream flow is compressing the marine layer, but by Sunday, onshore flow will return, dropping temperatures significantly—possibly below 85 degrees in areas that threatened 100 on Thursday.
“The marine layer will return with a vengeance,” Bain said.
In addition to fire and heat hazards, coastal areas face high tides and potential flooding. A coastal flood advisory is in effect from Wednesday night along the North Bay ocean coast and Thursday along the San Francisco Bayshore, with waves expected up to 1.5 feet above ground level in low-lying areas.
The beach hazards statement for sneaker waves and rip currents expired Wednesday, but high tides will persist through Saturday.
PG&E has not yet announced specific shutoff areas but is monitoring conditions closely. Residents are urged to prepare for possible outages, avoid activities that could spark fires, and stay hydrated during the extreme heat.