Fire Danger Levels

Have you ever entered a national forest and seen a sign indicating today's fire danger levels? It's one way national forest fire managers can quickly alert visitors about fire danger. Watch for the signs (see sample below) along forest roads and entrances, visitor recreation areas or ranger stations or contact your local, state, or federal fire agency(s), to get the official Fire Danger Rating.

Knowledge of these levels can help forest visitors make decisions about having a campfire. Homeowners may choose to postpone burning a debris pile if they are aware of the fire danger level for that day. Contractors working in the forest may consider extra precautions (like having a lookout) when using equipment that might produce sparks. In some cases, the National Forest may restrict or ban certain activities based on the fire danger levels. Learn more about restrictions.

What is the National Fire Danger Rating System?

The National Fire Danger Rating System (NFDRS) is a system that allows land agencies to estimate today’s or tomorrow’s fire danger for a given area. 

The symbols and adjectives shown below are to alert the public of fire danger levels, using adjectives and colors based on criteria established by the National Fire Danger Rating System.

The goal is to encourage the public to adapt their behavior and obey restrictions based on their knowledge of these levels. Read the definitions below, thensee how they relate to how danger levels are determined.

• IGNITION: A rating of the probability that a firebrand will cause an actionable fire.
• SPREAD: A rating of the forward rate of spread of the head of a fire.
• SPOTTING: Behavior of a fire producing sparks or embers that are carried by the wind and which start new fires beyond the zone of direct ignition by the main fire.
• CONTROL: The completion of control line around a fire, any spot fires therefrom, and any interior islands to be saved; burned out any unburned area adjacent to the fire side of the control lines; and cool down all hot spots that are immediate threats to the control line, until the lines can reasonably be expected to hold under the foreseeable conditions.

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 LOW FIRE DANGER

Fires do not readily start.Fires that do start, spread slowly and usually are easy to control.

IGNITION: Fuels do not ignite readily from small firebrands although a more intense heat source, such as lightning, may start fires in duff or dry rotted wood.

SPREAD: Fires in open cured grasslands may burn freely a few hours after rain, but woods fires spread slowly by creeping or smoldering, and burn in irregular fingers.

SPOTTING: There is little danger of spotting.

CONTROL: Easy

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 MODERATE FIRE DANGER

• Fires can start from most accidental causes, but the number of starts is generally low.
• Fires burn at moderate intensities. Fires will burn actively; heavy fuels will burn hot.

IGNITION: Fires can start from most accidental causes, but with the exception of lightning fires in some areas, the number of starts is generally low.

SPREAD: Fires in open cured grasslands will burn briskly and spread rapidly on windy days. Timber fires spread slowly to moderately fast. The average fire is of moderate intensity, although heavy concentrations of fuel, especially draped fuel, may burn hot.

SPOTTING: Short-distance spotting may occur, but is not persistent.

CONTROL: Fires are not likely to become serious and control is relatively easy.

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HIGH FIRE DANGER

Fires start easily from most causes.Control of fires can become difficult if not attacked promptly, especially in heavy fuels.Most fires can be controlled within the first day of burning.

IGNITION:
All fine dead fuels ignite readily and fires start easily from most causes. Unattended brush and campfires are likely to escape.

SPREAD:
Fires spread rapidly. High-intensity burning may develop on slopes or in concentrations of fine fuels.

SPOTTING:
Short-distance spotting is common.

CONTROL:
Fires may become serious and their control difficult unless they are attacked successfully while small.

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 VERY HIGH FIRE DANGER

Fires start easily and spread quickly.Fire is resistant to control and there is a high potential for large fires. Fire behavior is often erratic. “Blow up” potential is high.

IGNITION: Fires start easily from all causes.

SPREAD: Immediately after ignition, spread rapidly and increase quickly in intensity. Fires burning in light fuels may quickly develop high intensity characteristics such as long-distance spotting and fire whirlwinds when they burn into heavier fuels.

SPOTTING: Spot fires are a constant danger; long distance spotting likely.

CONTROL: Resistant to control.

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EXTREME FIRE DANGER

Severe fire conditions exist. The potential for fire disaster is high. Direct attack of fires is virtually impossible. Fires often escape first attack. Fire behavior is erratic. Fires are not usually controlled until fire danger subsides. 

IGNITION: Fires start quickly and burn intensely. All fires are potentially serious.

SPREAD: Furious spread likely, along with intense burning. Development into high intensity burning will usually be faster and occur from smaller fires than in the very high fire danger class.

SPOTTING: Spot fires are a constant danger; long distance spotting occurs easily.

CONTROL: Direct attack is rarely possible and may be dangerous except immediately after ignition. Fires that develop headway in heavy slash or in conifer stands may be unmanageable while the extreme burning condition lasts. Under these conditions the only effective and safe control action is on the flanks until the weather changes or the fuel supply lessens.