What does it mean when a wildfire is ‘contained’ or ‘controlled’? Know these key terms

If a wildfire has been 100 percent contained, does that mean it’s out? What about controlled?

What do those containment percentages in daily fire updates mean, anyway?

The California Department of Forestry and Fire Protection uses a variety of technical firefighting terms in its incident reports on wildfires burning across the state — including the Palisades Fire in Los Angeles County.

As on Thursday, Jan. 9, the Southern California wildfire had burned more than 17,000 acres and was 0% contained, Cal Fire said.

The blaze is part of a massive firestorm that has killed at least five people, destroyed more than 2,000 structures and forced 130,000 people to evacuate.

Fires ranging in the Los Angeles area include the Eaton Fire near Pasadena and the Sunset Fire in the Hollywood Hills.

Here’s a basic glossary to terms used to describe wildland fires, according to the National Wildfire Coordinating Group:

What does wildfire containment mean?

Containment, normally expressed as a percentage, indicates how much of the fire has been enclosed by a control line.

A wildfire with 25% containment means control lines have been completed around 25% of the fire’s perimeter.

Control lines are constructed or natural barriers used to stop a wildfire from spreading, also called firebreaks or fuel breaks.

Firefighters sometimes create them with controlled burns to remove fuel before the wildfire reaches it.

What’s the difference between contained and controlled fires?

Controlled fires are not only contained, but have been burned out along the interior of the control line with any hot spots threatening the line cooled down.

The control lines are expected to halt the spread of a controlled fire under reasonable conditions.

This story was originally published January 9, 2025 at 7:27 AM with the headline "What does it mean when a wildfire is ‘contained’ or ‘controlled’? Know these key terms."