Fire Weather Indices (FWI)

The Forest Fire Weather Index (FWI), developed by the Canadian Forest Service (Wang et al., 2015), is used and calculated from ERA5 reanalyses data. Initially, this index is calculated over a season based on weather observations available at noon local time (17:00 UTC), i.e., from the 24-hour temperature, relative humidity, wind speed, and precipitation variables, as well as the previous day's fuel moisture conditions as defined in Van Wagner and Pickett (1985). This method has been modified by a more physical approach by taking into account, instead of the time set at noon local time, the time when the sun is at its zenith (solar noon).