FIRE WEATHER INFORMATION
fwi

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Chandler Burning Index - The Chandler Burning Index uses the air temperature and relative humidity to create a numerical index of fire danger. That number is then equated to an Adjective Fire Danger ranging from LOW to EXTREME.

Fine-Fuel Moisture Code - Differences resulting from danger-rating calculations based on these new fine-fuel moisture content tables for the cured, transition, and green herbaceous stages of fuel are provided.

Initial Spread Index - Numerical rating of the expected rate of fire spread. It combines the effects of wind and the Fine Fuel Moisture Code on rate of spread without the influence of different fuel types.

Duff Moisture Code - Numerical rating of the average moisture content of loosely compacted organic layers of moderate depth. This code gives an indication of fuel consumption in moderate duff layers and medium-size woody material.

Fire Weather Index - Rating of fire intensity that combines the Initial Spread Index and the Buildup Index. It is suitable as a general index of fire danger throughout the forested areas of Canada.

Build Up Index - Numerical rating of the total amount of fuel available for combustion that combines the Duff Moisture Code and the Drought Code.

Drought Code - Average moisture content of deep, compact, organic layers. This code is a useful indicator of seasonal drought effects on forest fuels, and amount of smouldering in deep duff layers and large logs.

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FIRE  WEATHER INDEX
Rating and Color Code Description
LOW
FWI= 7.0 and less 		Fuels do not ignite readily from small firebrands although a moreintense heat source, such as lightning, may start fires in duff or punky wood. 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. There is little danger of spotting.
MODERATE
FWI= 7.0 - 15.9		 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
FWI= 16.0 - 24.9		 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
FWI= 25.0 - 30.9		 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
FWI=31.0 and higher		 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.