Fire Values Guide
Canadian Fire Weather Index (FWI) System
The standard system used across Canada — and globally — to assess fire danger from four daily weather observations.
How It's Calculated — The FWI Chain
Four weather inputs feed into moisture codes, which combine into fire behaviour indices, producing the final FWI danger rating.
Danger Rating Scale
Data Source
FWI data on the Detection Map is sourced from the BC Wildfire Service SFMS (Spatial Fire Management System) API, which provides daily FWI grid values across British Columbia derived from Environment and Climate Change Canada weather observations.
The FWI System was developed by the Canadian Forest Service and is described in: Van Wagner, C.E. (1987). Development and Structure of the Canadian Forest Fire Weather Index System. Forestry Technical Report 35. Canadian Forestry Service, Ottawa.
Reading the FWI Dashboard
The Fire Weather Index combines temperature, humidity, wind, and fuel moisture into a single number that predicts fire intensity under standard conditions.
FWI is the backbone of fire danger forecasts worldwide. Our Dashboard shows the FWI value alongside its six sub-indices: fine fuel moisture, drought code, duff moisture, buildup, initial spread, and fire load. Values above 30 typically trigger operational restrictions; values above 50 indicate extreme behaviour potential. The Dashboard updates hourly during fire season.