Parched Northern California landscape poised for early, prolonged wildfire season ahead

Anyone who’s been out in the countryside lately will have seen it: The browning of hillsides that were once brilliant green from winter rain.

It’s a normal part of seasonal change in Northern California, where sun-ripened grasses turn the region’s hills to golden brown.

Trouble is, it’s happening six or eight weeks ahead of usual, raising the specter of an early start to the summer fire season.

A prolonged dry spell that has drawn the region into a third year of drought has turned the landscape so dry that early April conditions more closely resemble those typical of late May or June.

Plant moisture data, the kind of thing monitored closely by fire weather watchers and emergency service personnel, has put fire intensity potential way above average and into record territory for most of the past six weeks.

Local Cal Fire officials are calling up seasonal workers a month and a half earlier as a result, bracing for long, tough months to come. And they’re preaching prevention and defensive maintenance in the strongest terms, knowing grasslands, brush and forests will only grow more combustible as the year wears on.

“Optimistically, we can control ignitions by being safe, and if we can control our ignitions that means there’s less fires,” said Cal Fire Battalion Chief Marshall Turbeville, noting lightning remains outside humans’ control.

“We need to be hypervigilant about what we do out there,” Cal Fire Division Chief Ben Nicholls said. “It’s one spark. It’s one bad day.”

It should surprise no one that drought years produce dry vegetation. But this strange weather year — front-heavy with rain in October and December, then almost nothing the past three months — has complicated matters, priming the pump for rapid plant growth first, then leaving it largely high and dry as the calendar flipped to 2022.

Green-up of wild grasses and fresh shrub growth peaked ahead of normal. Absent new growth, grasses have begun dying and shrubs are accumulating less water than they would be if they were still sprouting, said meteorology professor Craig B. Clements, director of the Wildfire Interdisciplinary Research Center and the Fire Weather Research Laboratory at San Jose State University.

Local land stewards have noticed for months what Brian Peterson, a fire ecologist with Audubon Canyon Ranch, called “a really early botany year,” in which the growing season was hastened by several early atmospheric rivers but has now left grasses going to seed early and drying out.

Said Bob Neale, stewardship director at the Sonoma Land Trust, “We’ve been talking about these very things since December, actually, after getting all that rain and seeing the faucets turned off.”

Live trees still are showing brilliant green with new leaves, but drying grasses mean forage is low for livestock and even some types of wildflowers are less abundant, he said.

More worrisome are the trees damaged in earlier fires that are suddenly giving up and falling over on land trust properties around Sonoma County. It’s unclear, however, whether that’s because of previous damage, the extended drought or a combination of factors, Neale said.

Dead logs — forests full of them, unburned for decades, from Forestville west to the coast — are what give Turbeville the most anxiety.

He fears the March 1 Alpine fire, which charred 21 acres of thick forest above Monte Rio, was a harbinger of a summer wildfire season extended by parched plant life.

“We’re not freaking out about it at this point,” Turbeville said.

“It’s just the realization that we talk about the fire season being year-round, but basically the onset of the summer fire season is getting earlier and earlier,” and with it “the impending doom of the fire season — a reminder that it’s going to be here sooner, rather than later.”

Chamise, a woody shrub common to California’s chaparral plant communities, is widely sampled around the state to measure plant moisture content or how much water there is in vegetation relative to plant material.

Live samples collected April 1 from a site near Los Gatos that has been used consistently over the past decade to monitor moisture content showed both old and new growth at record low levels, with values more commonly reached in late May or June, according to the findings from Clements’ lab.

Though the samples were taken about 110 miles south of Santa Rosa, the results should be reflective of conditions in Sonoma County, Clements said. They also are mirrored in values from numerous PG&E sites and other samples around the region, showing plant moisture peaking a month or more early this year, he said.

Plants generally contain lots of moisture, so at peak growing season they can have values well above 100% before dropping below that mark as they return to dormancy in fall and winter. Moisture content in chamise of around 60%, common to late summer and early fall, is considered critical level, Nicholls said.

New growth in Clements’ samples is still around 100%, but second-year growth already is trending down around 70%, even before the sun exposure of long summer days.

Clements said he hoped “to see a little bump” in mid-April samples from late March rain, but fire officials were skeptical, especially given high temperatures and dry, offshore flows in recent days.

“What it will do is just completely wipe out any respite we got from the rainfall we got last week or two weeks ago,” Nicholls said of the three-day heat wave.

Dead fuels are assessed separately — from fine, flashy fuels like cured grass to 8-inch logs on the forest floor — through modeling that takes into account how quickly different densities respond to either high humidity or hot, dry air in the surrounding environment.

They include four general classifications defined by size and the related time — 1-hour, 10-hour, 100-hour and 1,000-hour — that it takes for them to respond to ambient conditions. Larger logs 3 to 8 inches in diameter take the longest, about 1,000 hours. The drier they are, the more heat energy can go directly into the fire, instead of evaporating moisture content.

Dead fuel moisture levels reported each day by the Northern California Geographic Coordination Center for the midcoast to Mendocino area show values flirting with 30-year records for dryness as early as Feb. 12 and, in denser fuels, setting new records consistently even through rainfall March 27 and 28.

The Energy Release Component, or ERC, is a composite fuel moisture index that accounts for dead and live fuels in a given region. It is commonly consulted as a predictive measure of potential fire intensity.

Technically, the ERC is a measure of the total available energy per square foot at the head of the fire. Practically, it’s a signal of how fiercely a wildfire might burn.

On a line graph, it goes up as fuel moisture levels go down.

Already, the region’s energy release component is at a point that’s typical for June 4.

Tom Knecht, pre-fire division chief for Cal Fire’s six-county Sonoma-Lake-Napa unit, said the increased potential for severe fire is driving early hiring of 120 seasonal firefighters coming on Monday, a month and a half early, to be on hand to tackle expected grass fires in the coming weeks.

The incoming firefighters include 10 engine crews, the helitack crew for Boggs Mountain and an extra 40-person hand crew formerly stationed in Solano County to offset the reduced availability of inmate crews that has been a problem in recent years. Also included are firefighters for the service center warehouse in St. Helena who will deliver equipment and resources to the fire lines when blazes occur, Knecht said.

The hand crew eventually will take up residence on the county’s Los Guilicos campus near Oakmont. Hand crews provide vital service, especially in remote, rugged areas, building fire lines, dousing hot spots and setting backfires during wildland firefights.

A second wave of 50 seasonal personnel will come on board May 16, ensuring one extra engine is on-duty at each Cal Fire station. The Sonoma Air Attack base also is scheduled to open then. On May 30, 90 more firefighters come on, raising staffing to 31 engines in the unit, or peak staffing, Knecht said.

“These fuel indicators are what are driving these decisions, basically, justifying our budget decisions,” he said.

Even though the days will still get much longer later this summer, exposing the landscape to the sun’s heat and reducing overnight recovery potential, “we know we’re going to have grass fires (before then) and we know these 100-hour and 1,000-hour fuels are already dry.”

“I would say we’ll be in peak fire season a month and a half early,” Knecht said.

At the same time, tinder dry conditions don’t mean catastrophic fire is inevitable. Extreme wind has proven more decisive a driver of wildfire disasters.

Only 3 percentage points separated live fuel moisture values from samples taken at the Geysers during a critically dry period in advance of the October 2017 firestorm that devastated the North Bay amid hurricane-force winds and those taken in October 2021, a year in which the region escaped a major wildfire.

Live fuel values in June 2019 were high after drenching storms and local flooding three months earlier. It was followed by what Nicholls recalled as “a real unexciting fire season — right up until the wind event that happened at the time of the Kincade fire, and we have the largest fire in county history with the largest evacuation.”

By the time the Kincade started late Oct. 23, 2019, plant moisture had dropped to critically low levels, records show.

But it was fierce winds that fanned flames sparked by a worn jumper cable on high voltage, PG&E power lines and whipped the fire across 77,758 acres, more than 121 square miles, over the terrifying week that ensued.

What fire officials fear this year is the increased opportunity that dry fuels present for wildfire starts and advancement.

Wet fuel will not ignite until the moisture in it is vaporized, a process that consumes some of the energy that otherwise would have gone into the fire. But dry fuel catches and carries fire more readily, enhancing potential.

“When your fuels are where they’re supposed to be for a normal June in April,” Nicholls said, “that just expands out the period of time, the window of opportunity, for major fires because fuel conditions are ready to carry fire.”

What’s important now, he and others Cal Fire officials said, is for the public to ensure the space around their homes is clear and defensible and that they are cautious with anything that could spark a fire.

“It’s routine tasks people don’t think about — you get a flat tire and you pull off into the grass, you flick a cigarette, you mow the grass in the afternoon and hit a rock,” said Turbeville.

“Control what we can. Make sure are homes are as safe as they can be, and be prepared to evacuate,” he said.

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.