Fire Danger

Fire Danger (NFDRS)

The National Fire Danger Rating System (NFDRS) rates how readily wildland fuels will ignite, spread, and resist control at a given place and time. Unlike the satellite detections on the Wildfires page — which show fires that are already burning — NFDRS describes the conditions: how dry the fuels are, and how a fire would behave if one started.

Ratings are calculated by the Fire Environment Mapping System (FEMS), the interagency system that ingests weather from the RAWS network and performs the NFDRS calculations. Coverage is the United States only.

Current Indices

Recent observations and the 7-day forecast for the stations configured on this instance. Ingested via the platform feeds addon and rendered from the record store at view time (no page churn).

If nothing renders above, the fems-nfdr feed source is not yet configured (see Configuration).

Reading the table

• type distinguishes an O (observation — what was measured) row from an F (forecast — what is predicted). The table runs oldest-first, so observations come first and the forecast follows.
• ERC (Energy Release Component) tracks the total heat available per unit area at the flaming front. It responds to the heavy, slow-drying fuels, so it moves slowly and is the best single number for seasonal dryness.
• BI (Burning Index) combines ERC with the Spread Component and scales roughly to expected flame length. It is the index most often used for staffing and preparedness decisions.
• SC (Spread Component) estimates the forward rate of spread, and is strongly wind-driven — so it can spike on a single windy day while ERC barely moves.
• IC (Ignition Component) is the probability, 0–100, that a firebrand landing in the fuel will start a fire that needs suppression.
• fm1hr / fm10hr / fm100hr are dead fuel moisture percentages for progressively larger fuel classes — roughly grass and litter, twigs, and branch-sized material. Lower means drier.

Every value is for a single station and its fuel model. NFDRS is a point calculation, not a map: a station describes its own site, and conditions a valley away can differ sharply.

What this page does not show

There is no adjective rating here (the familiar Low / Moderate / High / Very High / Extreme signs). That class is not published by the API — it is derived by comparing a station's current index against percentiles of that station's own multi-year climatology, and the thresholds are set locally by each unit. Showing a computed rating without those local thresholds would misstate an operational number, so the raw indices are shown instead.

For an official adjective rating, use the issuing unit's own posting or the NWS fire weather forecast for the area.

Data Source

Configuration

The live feed is served by the ngdpbase feeds addon (#685). Enable it and declare the source in the instance app-custom-config.json, then restart.

Keys are written in flat dot-notation below, matching how app-custom-config.json is written in practice (see also docs/volcano-sources.md). AddonsManager flattens ngdpbase.addons.feeds.* before the addon reads it, so a nested "sources": { ... } object works identically — but pick one style per file rather than mixing them.

{
  "ngdpbase.addons.feeds.enabled": true,
  "ngdpbase.addons.feeds.sources.fems-nfdr.adapter": "csv",
  "ngdpbase.addons.feeds.sources.fems-nfdr.url": "https://fems.fs2c.usda.gov/api/ext-climatology/download-nfdr-daily-summary/?dataset=all&presetDate=-5Days7Days&dataFormat=csv&stationIds=40611,45114,350912,241907,420403,291301,52301,92201,472603,500754,498012&fuelModels=Y",
  "ngdpbase.addons.feeds.sources.fems-nfdr.type": "Observation",
  "ngdpbase.addons.feeds.sources.fems-nfdr.intervalMinutes": 360,
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.station": "StationName",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.stationId": "StationId",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.date": "ObservationTime",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.type": "NFDRType",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.fuelModel": "FuelModel",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.erc": "ERC",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.bi": "BI",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.sc": "SC",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.ic": "IC",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.kbdi": "KBDI",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.gsi": "GSI",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.fm1hr": "1HrFM",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.fm10hr": "10HrFM",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.fm100hr": "100HrFM",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.fm1000hr": "1000HrFM",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.herbFm": "HerbFM",
  "ngdpbase.addons.feeds.sources.fems-nfdr.map.woodyFm": "WoodyFM"
}

Merge this into the existing sources keys — do not replace them. A live instance typically already carries several sources (firms-viirs, vaac-advisories, tsunami-alerts, and others); overwriting the block drops them silently, and the pages that depend on them go quiet with no error.

No API key is required for this endpoint, and none should be added — the download-nfdr-daily-summary path is open.

Choosing stations

stationIds is a comma-separated list of FEMS station numbers. The eleven above are one station per Geographic Area Coordination Center (GACC), chosen as the nearest NFDRS-producing station to each coordination area — a national overview rather than a local readout. Replace them with whatever suits your instance.

2,088 stations produce daily NFDRS across 53 states and territories, weighted heavily toward the fire-prone west (CA 407, OR 135, AK 117, MT 113). Stations can be browsed on the map at fems.fs2c.usda.gov, or the whole catalogue — with coordinates — can be listed in one call:

curl -s -X POST https://fems.fs2c.usda.gov/api/climatology/graphql/ \
  -H 'Content-Type: application/json' \
  -d '{"query":"query{stationMetaData(returnAll:true,nfdrsDailyVisible:TRUE){_metadata{total_count}data{station_id station_name latitude longitude state}}}"}'

That endpoint is the FEMS UI's own internal backend (/api/climatology/), not the documented external API (/api/ext-climatology/). It answers without a key today, but it is undocumented and carries no stability guarantee — treat it as a lookup tool for choosing station numbers, not as something to depend on at runtime. The documented external GraphQL surface exposes the same data but requires a FEMS API-role key via a FAMAuth account, and is POST-with-headers, which the feeds addon's GET-only rest-json adapter cannot call (see docs/wildfire-sources.md).

FEMS limits how many stations one request may span: unlimited under a 2-week window, 10 stations for 2 weeks to a year, and 1 station beyond a year. presetDate=-5Days7Days is a 12-day window, so it sits in the unlimited tier — but each station adds 12 rows per poll (the eleven above produce 132), so keep the list to a legible handful rather than a whole region.

fuelModels=Y selects the NFDRS 2016 fuel model used most widely for general reporting. Other models can be requested, comma-separated, but every model returns its own row per station per day.

Status: page and feed wiring live. For the full station map, historical data, and analysis tools, visit FEMS.

Related Pages

• Wildfires — satellite thermal hotspot detections for fires already burning
• Alerts — cross-hazard summary of what's currently active
• Attribution — credit and citation for every data source