Understanding of the National Fire Danger Rating System

The National Fire Danger Rating System (NFDRS) is a system that allows fire managers to estimate today's or tomorrow's fire danger for a given area. Managers use NFDRS to input data and to receive information used to determine fire danger in their area. Based on the fire danger, managers may impose restrictions or closures to public lands, plan for or pre-position staff and equipment to fight new fires, and make decisions whether to suppress or allow fires to burn under prescribed conditions.

The current National Fire Danger Rating System is utilized by all federal and most state agencies to assess fire danger conditions.

This system has remained static for nearly 40 years, despite many scientific and technological advances that could significantly improve the system. In 2000, work began to evaluate and refine the National Fire Danger Rating System. The updated version of the National Fire Danger Rating System, also known as NFDRS 2016, was completed during the fall of 2017 and went into service for testing/comparisons/evaluation during the 2018 fire season.

Adjective Class Rating

The "Adjective Ratings" are a public information description of the relative severity of the current fire danger situation in a general area. Since 1974, five rating levels have been used to describe danger levels in public information releases and fire prevention signing. Adjective Ratings are generally posted on signs as visitor enter public lands or at agency offices. Many people associate these signs as "Smokey Bear signs."

We use 5 different color-coded levels to help the public understand fire potential. The purpose of this is for visitors to understand the current conditions and help mitigate their actions to prevent human-caused wildfires. 

Fire Danger Rating and Color Code

Low (L, Dark Green)

Fuels do not ignite readily from small firebrands although a more intense heat source, such as lightning, may start fires in duff or punky wood. Fires in open cured grasslands may bum freely a few hours after rain, but woods fires spread slowly by creeping or smoldering, and burn in irregular fingers. There is little danger of spotting.

Moderate (M, Light Green or Blue)

Fires can start from most accidental causes, but with the exception of lightning fires in some areas, the number of starts is generally low. 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. Short-distance spotting may occur, but is not persistent. Fires are not likely to become serious and control is relatively easy.

High (H, Yellow)

All fine dead fuels ignite readily and fires start easily from most causes. Unattended brush and campfires are likely to escape. Fires spread rapidly and short-distance spotting is common. High-intensity burning may develop on slopes or in concentrations of fine fuels. Fires may become serious and their control difficult unless they are attacked successfully while small.

Very High (VH, Orange)

Fires start easily from all causes and, immediately after ignition, spread rapidly and increase quickly in intensity. Spot fires are a constant danger. 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.

Extreme (E, Red)

Fires start quickly, spread furiously, and burn intensely. All fires are potentially serious. Development into high intensity burning will usually be faster and occur from smaller fires than in the very high fire danger class. 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.