North Bay braces for prolonged, ‘oppressive’ heat wave, increased fire danger

When a brush fire broke out Wednesday afternoon in the 2500 block of Spring Hill Road in Petaluma, Cal Fire crews jumped on it quickly, stopping its spread within half an hour and holding it to 12 acres.

It's exactly the kind of situation firefighters are preparing for this Labor Day weekend as the entire Bay Area braces for what federal forecasters Wednesday called a wave of “oppressive heat” expected to arrive Friday with a span of triple-digit days that will mark the hottest on the calendar so far in 2017.

With it will come heightened risks for public health and an increased chance of what the National Weather Service called “explosive fire growth,” a potentially destructive and deadly outlook in what is typically the most active time of the year for wildfires in Northern California.

The last time the Bay Area had such a wide-scale and pronounced heat wave was July 2006, weather officials said.

In Santa Rosa, temperatures are forecast to climb to 107 degrees Friday and linger above 100 degrees through Sunday, dipping below triple digits Monday, when the high is set to reach 98 degrees.

In the northern part of the county and inland, it's expected to be even hotter, with the high in Cloverdale forecast to reach 109 degrees both Friday and Saturday. In Sonoma, the mercury is forecast to peak at 115 degrees on Friday and 112 on Saturday.

The forecast has already-busy fire crews on edge.

“We're concerned about the heat every day, but with this heightened temperature ... one spark could cause a wildland fire,” said Cal Fire spokeswoman Suzie Blankenship. “We've had our share of heat this year, and that means the brush is now critically dry.”

Still, Blankenship said, with crews on alert throughout the state, firefighters were “prepared to do their jobs as needed.”

The National Weather Service has issued a trio of public notices about the extreme weather: a heat advisory, an excessive heat warning and a red flag fire warning for a major swath of the Bay Area.

The most critical period for fire danger will be Friday night into Saturday morning, the Weather Service said, when humidity will be less than 30 percent and temperatures will remain in the 70s and low 80s overnight.

A large high-pressure ridge circling over the region could mean the heat will last into next week, shattering weather records and endangering public health from the South Bay to the North Bay, said meteorologist Brian Garcia with the National Weather Service.

“We think there could be a potential threat to life if cautions aren't taken,” he said, advising people to stay out of the sun, stay hydrated and avoid leaving children or pets in cars. “Pretty much everyone is going to be at risk if they don't take the necessary precautions.”

Santa Rosa will open the Finley Center at 2060 W. College Ave. from 11 a.m. to 6 p.m. Friday, Saturday and Sunday as a cooling location for those seeking to escape the heat, said Paul Lowenthal, Santa Rosa's assistant fire marshal. Animals will be accepted on a case-by-case basis.

“We want people to use it as an opportunity to relax, to not overdo it during the heat,” he said. “Pay special attention to kids, animals, the elderly - sensitive populations.”

In response to the heat wave, Pacific Gas & Electric Co. is advising customers to be conscious of their power usage and the risks to the grid.

“We are expecting more outages Friday and Saturday because of the heat,” said Deanna Contreras, spokeswoman for PG&E. “When we have a continuous number of days with high heat, it doesn't allow our equipment to cool off, and you see more equipment failure. ... And not only because the equipment doesn't cool; also because more people are using air conditioners and there's more demand from the grid.”

PG&E is boosting its staffing during the heat wave but advised customers to be prepared for outages by stocking water, flashlights and spare batteries.

“While Friday might not feel really hot,” said Garcia of the National Weather Service “after five days of that, you're going to wish it would break.”

You can reach Staff Writer Christi Warren at 707-521-5205