What is a red flag warning anyway? Wildland firefighting terminologies explained

SALT LAKE CITY (ABC4) — As fire season continues, you may be hearing a lot of different terms from firefighters and other officials as they track and fight wildfires. In case you find yourself reading wildfire updates and wondering what they mean, we’ve compiled some explanations.

You can find full glossaries of wildland firefighting terms from

Texas A&M Forest Service and the National Wildfire Coordinating Group, but here are some explainers for a few of the most common terms you will be hearing during wildfire season.

A big one that comes up frequently from weather forecasts is red flag warning. This is a fire weather forecaster term that is used to alert the public to an ongoing or imminent critical fire weather pattern. What this means is that the weather conditions make it very likely that a fire could spread and turn into a wildfire.

You may also hear firefighters refer to fires as confined, contained, or controlled, and all three terms have different meanings. They all refer to wildfire suppression strategies, however.

• Confining a fire is the least aggressive of these strategies. Usually, firefighters will allow the fire to burn itself out within natural boundaries–rocky ridges, streams, or roads, for example.
• Containing a fire means that it is surrounded by a fuel break, which can include natural barriers as well as lines constructed by firefighters. A contained fire is not extinguished yet!
• Controlling a fire surrounds the fire with a control line, forward progression has been stopped, and the fire is not expected to escape. The fire is not extinguished here yet either, but it is no longer a threat to surrounding homes or property.

Kelly Wickens, Prevention Specialist for Forestry Fire State Lands, State of Utah, explained a bit more about containment and what containment percentages mean in an interview with ABC4.com.

“When we talk about percentages, say the fire is 10% contained, that means that around the perimeter of the fire, we believe that 10% of that perimeter is secure,” Wickens said. “So, we do not think that the fire will cross in that area, so that means we are confident that in that area, that the fire will no longer progress.”

Wickens also said that containment percentages can fluctuate, and that can happen when the wildfire grows, usually in areas of the fire that were not considered contained.

“When we show containment, that doesn’t mean that the fire is out,” she added. “What it means is that we are making progress. We are managing the fire and to the best of our ability, stabilizing the situation.” She said that the fire being completely put out sometimes can take until the winter.

A line is a barrier made by firefighters against the fire. There are several different types.

• A control line is a general term for “all constructed or natural fire barriers” used to control a fire.
• A fireline is a “linear fire barrier that is scraped or dug down to mineral soil” (soil with little combustible material).
• A fire break is used to “stop or check fires that may occur” and can provide a control line for crews to work from.
• A wet line is a line made by spraying water or water and fire retardant to serve as a temporary control line.

Fuel refers to any flammable materials that can feed a fire. Different types of fuel include brush, duff, and litter, and firefighters may also refer to dead fuels, which are fuels with no living tissue (dead branches, grass, etc.). Flash fuels are fuels that ignite and are consumed rapidly–grass, leaves, pine needles, ferns, etc.

Firefighters also might say that a fire has been knocked down, which might sound like another way of saying that a fire has been put out, but it is different. When a fire has been knocked down, it means that firefighters have reduced the flame or heat on “vigorously burning parts” of a fire edge.

After a fire has been controlled, firefighters will say that they are mopping up the fire, which means that they are extinguishing the fire or removing burning material to make the fire safer and reduce smoke.

Alexa McFadden contributed to this story.