Marin County, California – Firefighters worked to extinguish remaining hot spots and strengthen containment lines on the Chileno Valley Fire on Wednesday, September 23, as crews operated across rural ranchland west of Petaluma. The Marin County Fire Department filmed the work.

The fire started Sunday, September 20, as multiple spot fires along Chileno Valley Road, about four miles south of Tomales Road. Marin County Fire, CAL FIRE LNU, Petaluma Fire, Gold Ridge Fire, CHP and other agencies stopped the forward spread that evening.

The fire was mapped at 341 acres. No structures were damaged and no injuries were reported.

A brief evacuation advisory for zone MRN-E118 was later lifted. Smoke drifted into Petaluma and parts of Sonoma County, prompting an air-quality advisory.

Flames also burned a pallet of tires on ranchland, producing dark smoke that initially led crews to believe a building was involved.

Containment increased from roughly 5% Sunday night to 45–50% Monday, 75% Tuesday, 85% Wednesday morning and 95% by the 3:45 p.m. update Wednesday.

Crews remained on scene strengthening lines and extinguishing hot spots. The cause remained under investigation. Weather at the time of ignition was cool and humid, with no nearby lightning reported.

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