Chance of dry lightning triggers fire weather watch for most of Sonoma County, North Bay

A year after lightning sparked the 55,209-acre Walbridge fire, Sonoma County is again on the verge of being hit by a dry lightning storm that, though smaller, could trigger more fires due to the North Bay’s ever-expanding withered landscape.

Concerns that dry lightning may develop across the North Bay on Thursday evening, prompted the National Weather Service to issue a fire weather watch which will take effect at 5 p.m. Thursday until 11 a.m. Friday.

Dry lightning is lightning that develops whenever storms don’t produce rain. This week’s conditions are expected to be “more dry than wet,” according to the weather service.

Last year, during one mid-August weekend, such storms dropped thousands of bolts of lighting on open land in various parts of California, igniting hundreds of fires, including the Walbridge fire in Sonoma County, and at least one in Oregon.

Despite the alert, weather service meteorologist David King said, Thursday’s anticipated conditions are considered normal for this time of year and are expected to be weaker than the "atypical“ lighting storm that sparked the Walbridge fire west of Healdsburg on Aug. 17, 2020.

Still, given the state of Sonoma County’s current drought-ridden landscape, he added, even a single lightning bolt could be cause for concern.

“With everything being as dry as it is, you do not need a 2020 lightning event from last year,” King said. “It just takes one spark.”

The fire weather watch is in effect for much of the North Bay, including Napa County and all but the western edges of Sonoma and Marin counties.

Elsewhere in the Bay Area, the East Bay hills and valleys and the Diablo Range are also included. The watch extends north into portions of northeast Mendocino County and all of Lake County.

Residents are urged to be cautious and avoid unnecessary activities near dry vegetation. This includes using power tools and warming equipment, including barbecues.

“We’re just asking people to be extra vigilant,” said Cyndi Foreman, Sonoma County Fire District division chief and fire marshal.

She said Sonoma County residents should prepare go-bags containing important documents and supplies, including protective equipment, such as face masks and hand sanitizer, to guard against COVID-19.

County residents should also acquire evacuation tags that they can attach to door knobs and mailboxes to indicate they’ve already left whenever authorities go home-to-home during evacuation periods.

The tags can be obtained from county law enforcement and fire agencies.

“It can save valuable time and even lives if people use these tags appropriately,” Foreman said.

Last year, North Bay residents saw first hand the type of damage a lighting-induced fire could do.

In addition to the Walbridge fire, dry lighting was blamed for several massive wildfires throughout the Bay Area and Northern California in 2020. They included the LNU Lightning Complex, which burned more than 363,000 acres and destroyed more than 1,400 structures across the North Bay east of Santa Rosa.

This year, concerns are compounded by the lack of rain that has the entire North Bay under “exceptional drought” conditions, according to the U.S Drought Monitor.

National Weather Service data shows Sonoma County hasn’t received any measurable rain since April 25 when less than one-tenth of an inch was recorded.

This week’s fire weather watch comes days after at least 14 roadside fires were sparked in dry vegetation in and around Healdsburg on Monday night, the largest growing to just under 2 acres.

Cal Fire investigators are still trying to determine how they sparked.

You can reach Staff Writers Colin Atagi at and Matt Pera at On Twitter @Matt__Pera.

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