Spontaneous combustion likely cause of barn fire near Petaluma

Officials now believe a barn full of hay that went up in flames outside Petaluma on Wednesday morning likely caught fire through spontaneous combustion, Sonoma County fire spokesman Brentt Blaser said Thursday.

“It’s very rare, but it can happen,” Blaser said. “At this point, that’s what they’re looking at as the root cause.”

Up to 500 tons of hay had been stacked inside the barn at a Chileno Valley Road dairy before the fire was reported around 2:30 a.m. Wednesday, fire officials said.

The fire was out on Thursday, though crews from the Wilmar Volunteer Fire Department were still checking for hot spots and cleaning up, Blaser said.

He said damage to the hay and the 60,000-square-foot barn was estimated at $250,000.

You can reach Staff Writer Mary Callahan at 521-5249 or On Twitter @MaryCallahanB.

Mary Callahan

Environment and Climate Change, The Press Democrat

I am in awe of the breathtaking nature here in Sonoma County and am so grateful to live in this spectacular region we call home. I am amazed, too, by the expertise in our community and by the commitment to protecting the land, its waterways, its wildlife and its residents. My goal is to improve understanding of the issues, to find hope and to help all of us navigate the future of our environment. 

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