More than just the FWI: Exploring all components of the Canadian Fire Weather Index System for International Fire Danger Rating Systems
Authors: Jurko Natasha , Wotton Mike , Hanes Chelene 
Published: October 2022

The Canadian Fire Weather Index (FWI) System has its origins in early Canadian fire research and resultant hazard rating systems dating back to the 1930s. Today the FWI System is one cornerstone of the larger Canadian Forest Fire Danger Rating System (CFFDRS), which is comprised of several sub-systems, each evaluating fire potential at different scales and resolutions. The other major sub-system in the CFFDRS is the Fire Behaviour Prediction (FBP) System, designed to give quantitative predictions of fire behaviour in specific situations under constant conditions. Whereas the FBP System requires information on fuels, weather and landscape features to calculate potential fire behaviour on variable timescales, the FWI System provides a set of six daily outputs derived from weather observations, each indicative of different aspects of potential fire activity useful in fire management planning. The basic design of the FWI System and simple inputs has made it a popular choice for adaptation in other regions. The System outputs can be readily adapted to act as the foundation for a new fire danger rating system or as an enhancement to an existing system. Research exploring the utility of the FWI System for characterizing fire activity in a region often focus on the final indicator, the FWI (not to be confused with the System namesake). While the FWI (the indicator) is a highly useful indicator of potential fire intensity, it is not necessarily the most appropriate indicator from the FWI System to capture specific fire management needs. In adapting the FWI System to a new jurisdiction to support fire management, one should consider how each indicator from the System could inform the specific fire management needs in a region; that is, which of the Systemâ€™s six outputs relate most closely to important aspects of fire activity. Furthermore, it is important understand how the standard Canadian pine fuel type might differ from those in the region in question. This paper will review examples of how each of the elements of the FWI System are used in operational fire management planning in Canada, and present Canadian Forest Service (CFS) experience in adapting the FWI System to other jurisdictions. We will evaluate each of the six components of the FWI System and their use to describe different aspects of fire potential in the wildland fire environment. While grounding this discussion in the way the System outputs are used to inform operational fire management decision-makers in Canada, we will also discuss their potential adaptation to support fire management planning in other locations. We will touch on the question of adaptation of the System to different fuels, and how these might effect the interpretation of each component and, how these considerations can lay the foundation to building local fire behaviour predictors. While there is no set recipe for adaptation of the FWI System to a new region, understanding what each element of the wildland fire environment the FWI System outputs are designed to track is a critical first step.