Design Fire Weather Index (current)
How dangerous the fire weather gets on a site's worst days of the year — the wildfire intensity the loss engine reads, and the classes the Resilience panel grades it on.
Source: NASA NEX-GDDP-CMIP6, ensemble mean of GFDL-ESM4 / MPI-ESM1-2-HR, FWI computed with xclim Year: 2030-2040 window (current-conditions band) Category: Physical risks · Direct Physical Loss engine inputs Coverage: Global Format: Raster grid (0.25° source grid) Used in risk analysis: No screening flag. It feeds the Direct Physical Loss wildfire channel and grades the wildfire exposure of the Resilience panel
What it shows
How dangerous the fire weather gets at a location on its worst days of the year: the 98th percentile of the daily Fire Weather Index (FWI) over a year. The FWI combines temperature, humidity, wind and rain into one number for how readily a fire starts and spreads. It is a design value, the fire weather a site meets a few days each year, and says nothing about whether there is fuel nearby to burn.
How it is built
Daily FWI is computed from NASA NEX-GDDP-CMIP6 downscaled climate with xclim, for two models averaged together, then reduced to its yearly 98th percentile. The current-conditions band is the 2030-2040 window, the one closest to the 2026 reference year; the emissions scenarios coincide that early, so one file serves all of them.
How to read it
Read it as a class. The map and the Resilience panel both place the value in the six fire danger classes of the European Forest Fire Information System (EFFIS). EFFIS publishes them for a daily FWI. Here they are read on the yearly p98: a site's class is the one it reaches on its 98th-percentile fire-weather day.
Class thresholds
| Class | FWI (yearly p98) |
|---|---|
| 1 - Very low | below 5.2 |
| 2 - Low | 5.2 to 11.2 |
| 3 - Moderate | 11.2 to 21.3 |
| 4 - High | 21.3 to 38.0 |
| 5 - Very high | 38.0 to 50.0 |
| 6 - Extreme | above 50.0 |
How these thresholds were set. They are the EFFIS fire danger classes, taken as published. Darwin sets no cut point of its own on this layer. The wildfire exposure grade of the Resilience panel reads these same classes, so the map and the panel cannot place a site in two different classes.
Why this layer
It is the fire-weather half of the wildfire loss: the engine multiplies how often the land around a site burns (the observed burned-area fraction) by how intense a fire this weather can carry. The two already multiplied are on the wildfire annualised loss sheet. The wildfire risk page explains the damage function.
Legend
Symbolised field: FWI
| Value (FWI) | Label | Colour |
|---|---|---|
| 0.0 | 1 - Very low (<5.2) | #ffffb2 |
| 5.2 | 2 - Low (5.2–11.2) | #fed976 |
| 11.2 | 3 - Moderate (11.2–21.3) | #fecc5c |
| 21.3 | 4 - High (21.3–38.0) | #fd8d3c |
| 38.0 | 5 - Very high (38.0–50.0) | #f03b20 |
| 50.0 | 6 - Extreme (>50.0) | #bd0026 |
Generated from darwin/tools/darwin-geo/darwin-layers/fwi_design_current/layer.toml and risk_indicator_pairs.toml (develop).