Initial Spread Index

Numerical rating of the expected rate of fire spread.

Description & Technical Information


The Initial Spread Index (ISI) is a variable of the Fire Weather Index rating system designed and adopted by the Canadian Forest Service. This is an indicator of the expected rate of fire spread. The FWI integrates current ISI and BUI to produce a unitless index of general fire intensity.

Technical information

Coverage Global
Horizon 10 days
Time Resolution 1 day
Spatial Resolution O1280, ~9 km [HRES]; O640, ~18 km [ENS]
Update Once a day following either the 00 UTC ECMWF forecast release.
Nature Raster Maps
Availability , , ,

Model or Algorithm