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Fire Danger Background

General References

Fire Danger ratings are an effective part of daily risk rating and operational preparedness for fire management agencies across the world.  Chapter 10 (Preparedness) of the Interagency Standards for Fire and Fire Aviation Operations outlines processes and resources applied in the development of standard Fire Danger Operating Plans in the United States.

Included in Fire Danger Operating Plans are:

  • Specification of fire danger ratings
  • Identification of climatological thresholds for administrative purposes. Default thresholds include the 90th and 97th percentile values for key indices in the applied system. The Bureau of Land Management (Department of Interior) uses the 80th and 95th percentiles instead.
  • Communication of those danger ratings, including both internal and external forms.

Some valuable links:

A variety of fire weather systems are applied in danger rating around the US. There are primarily two systems used in fire danger operating plans.

US National Fire Danger Rating System (NFDRS):

First introduced in 1964, NFDRS has been updated in 1972, 1978, 1988, and now 2016 to integrate newer science and improved processing. This guide will compare important aspects of the 1978, 1988, and 2016 versions, detail important outputs, and describe primary components and indices. More information about the system and the latest update to it can be found at:

CFFDRS Fire Weather Index (FWI) System

Introduced in Canada in 1970. Implemented in Alaska and the lake states of Michigan, Minnesota, and Wisconsin in the early 1990s. Details about CFFDRS are included a separate section of this guide. These websites provide data access

Other tools, formulations, and applications are used locally across the country. Some examples are highlighted later, in section 4.5

78/88 Version NFDRS Structure

2016 Version NFDRS Structure


NFDRS Version Comparison