Updates on California wildfires.
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Updated: 7:02 a.m. Sep. 21
First discovered: 13 hours ago, 5:37 p.m. Sep. 20
Initial location: Chileno Valley Road and Bordessa Road west of Petaluma, Marin County, Calif.
Fire unit: Marin County Fire Department
Fire type: Wildfire
Fire name: Chileno Fire
Chileno Fire initially started at 5:37 p.m. Sep. 20 on Chileno Valley Road and Bordessa Road west of Petaluma in Marin County, California.
As of Monday morning, 341 acres of land had been destroyed by it. By Monday morning, the fire crew succeeded in containing 45% of the wildfire. Currently, there is no information available on the cause of the fire.
Fire containment
What does it mean for a fire to be 45% contained?
The percentage indicates how much of the fire perimeter has been surrounded by a control line. In this case, it means that 45% of the wildfire is halted from spreading, while 55% is still uncontrolled.
Containment is part of a larger plan for managing a wildfire. It is normally expressed as a percentage and it refers to how much of the fire perimeter has been surrounded/enclosed by a control line that firefighters create. The containment percentage indicates a certain level of control, but it doesn’t always correlate to safety level. Also, it’s important to note that containment doesn’t mean a fire is out.
How is containment measured?
The incident’s central command constantly receives progress reports from firefighters on the ground. As the fireline is constructed, inspected or reinforced, mappers record those details to adjust the containment percentage. The percentage tells the public how much of the fire perimeter is believed to not go beyond the control lines.
Source: Cal Fire
United Robots Sacramento
This story was originally published September 21, 2026 at 7:25 AM.