Canadian Forest Service Publications

An approach for defining physically based Fire Weather Index System classes for Ontario (Information Report GLC-X-29). Hanes, C. C.; Wotton, B.M.; McFayden, C. and Jurko, N. 2021. Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre. Information Report GLC-X-29. 35 p.

Year: 2021

Issued by: Great Lakes Forestry Centre

Catalog ID: 40501

Language: English

Series: Information Report (GLFC - Sault Ste. Marie)

Availability: PDF (download)

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Plain Language Summary

The Canadian Fire Weather Index (FWI) was introduced nationally in 1969 as a system of codes and indices based on four weather observations (temperature, relative humidity, wind speed, precipitation). These codes and indices are commonly interpreted and communicated using a classification system (e.g., Low, Moderate, High, Extreme) by fire management agencies. The original classes for the FWI system were determined assuming a small number of the “worst” days in the fire season should be classified as Extreme and most of the days classified as Low. Using Ontario as an example, this information report introduces an approach to update the way FWI system classes are determined by associating one important characteristic of wildland fire (for example, rate of spread) to each code and index. The report compares these two approaches using twenty-eight years of historical weather and fire records.