Wildfire Containment and Control: What the Terms Mean

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Firefighters battle flames from the Palisades Fire in the Pacific Palisades neighborhood of Los Angeles, Calif. on Jan. 7, 2025.

As wildfires rage, authorities are battling to contain the blazes, which the public can monitor via a state-provided online service from the Department of Forestry and Fire Protection.

By Thursday evening, the Hollywood Hills fire, which ignited on Wednesday, was fully contained. However, five other fires—including the initial and largest blaze—along with the Eaton, Kenneth, Hurst, and Lidia fires remain active and pose significant threats to life, property, and natural resources.

But what does it mean when a fire is reported as 0% contained—like the Eaton and Kenneth fires—or at 6% (Palisades), 10% (Hurst), or 60% (Lidia)?

The National Wildfire Coordinating Group (NWGC) defines wildfire containment as achieving a completed control line around the fire and any related spot fires, effectively halting further spread.

These control lines, as detailed in a CAL FIRE factsheet on the 2021 Caldor fire, can be natural features (rivers) or man-made barriers (firebreaks). Containment measures the proportion of the fire perimeter encircled. A 30% contained fire signifies barriers around 30% of its perimeter, representing both linear progress and confidence levels.

However, 100% containment doesn’t equate to control or extinguishment. The CAL FIRE factsheet clarifies that a 100% contained fire might still burn internally within the control line, requiring further suppression and repair work before closures are lifted.

In 2014, it was highlighted that even 100% contained fires could spread due to strong winds breaching control lines. The Wildfire Control Foundation of America (WFCA) defines “contained” as indicating a high confidence, though not a guarantee, that flames won’t surpass the barriers.

Following containment, the next phase is control, meaning extinguishment within the control line, with remaining hotspots cooled. The NWGC defines “controlled” as encompassing a completed control line around the fire and spot fires; burnout of unburned areas adjacent to the control lines; and cooling of all immediately threatening hotspots, ensuring the lines hold under foreseeable conditions.

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