Fire danger indexes

Canadian Model

Ffmc_o_medium Fine Fuel Moisture Code
Ffmc_legend
Ffmc_f_medium
Dmc_o_medium Duff Moisture Code
Dmc_legend
Dmc_f_medium
Dc_o_medium Drought Code
Dc_legend
Dc_f_medium
Isi_o_medium Initial Spread Index
Isi_legend
Isi_f_medium
Bui_o_medium Buildup Index
Bui_legend
Bui_f_medium
Fwi_o_medium Fire Weather Index
Fwi_legend
Fwi_f_medium

Interpretation

The following chart is a statewide generalized fire danger rating chart for the Canadian Fire Weather Index. It is based on a five class danger rating system, i.e., low, moderate, high, very high , and extreme. The distribution is based on weather records from 1985 - 1998. Low days occurred 45% to 50% of the time, moderate - 30 %, high days - 12% to 15%, very high days occurred 7%-8% of the time, and extreme days were 2%-3%. This is not meant to be used as a staffing guide . Each area needs to look at its own weather data coupled with its fire occurrence data. For instance, if you have a drought code of 380, it does not mean you are in extreme fire danger. It means that the drought code only gets that high on 2% of the days between April 1 and November 1.

Index Low Moderate High Very High Extreme

FFMC

0.0 - 80.9

81.0 - 87.9

88.0 - 90.4

90.5 - 92.4

92.5+

DMC

0.0 - 12.9

13.0 - 27.9

28.0 - 41.9

42.0 - 62.9

63.0+

DC

0.0 - 79.9

80.0 - 209.9

210.0 - 273.9

274.0 - 359.9

360.0+

ISI

0.0 - 3.9

4.0 - 7.9

8.0 - 10.9

11.0 - 18.9

19.0+

BUI

0.0 - 18.9

19.0 - 33.9

34.0 - 53.9

54.0 - 76.9

77.0+

FWI

0.0 - 4.9

5.0 - 13.9

14.0 - 20.9

21.0 - 32.9

33.0+

Definitions

Fine Fuel Moisture Code (FFMC)

This provides a relative indicator of the moisture in the fine fuels. Like the 1 hour fuel moisture, it reacts directly with the air temperature and relative humidity.

Duff Moisture Code (DMC)

This is an index of the moisture of the loosely compact organic layers at a depth of 2-4 inches.

Drought Code (DC)

This measures long term dryness in the fuels. It is a longer term index than the NFDRS 1000 fuel moisture. It doesn't reflect the probability of fire occurrence by itself, but can be useful in predicting the level of mop up needed and the consumption of large fuels. It should be looked at in relation to peat fire starts.

Initial Spread Index (ISI)

This is based on the FFMC and the wind speed. It provides a relative numerical rating of the expected rate of spread. This is similar to the NFDRS Spread Component.

Buildup Index (BUI)

This index is based on the DC and the DMC. It provides a relative indication of the amount of fuel available for combustion. This is somewhat similar to the NFDRS Energy Release Component. It doesn't predict what a given day might be like, but does relate well to the dryness of the fuels.

Fire Weather Index (FWI)

This combines the BUI and the ISI to give a relative numerical rating of fire intensity. It can be compared to the NFDRS Burning Index.