Fire Weather Index — BC Wildfire Edition
The Canadian Forest Fire Weather Index (FWI) System applied to British Columbia. Same CFFDRS equations as Alberta — different danger thresholds, fuel types, fire centre regions, and data sources. BC uses a 5-class danger scale without "Very High"; thresholds calibrated to BC's wetter climate and lodgepole-pine-dominated landscape.
FFMC
Fine Fuel Moisture Code. Numerical rating of the moisture content of litter and other cured fine fuels. Critical indicator of ease of ignition and flammability. In BC's coastal forests, high humidity suppresses FFMC; interior valleys dry rapidly under Chinook-like inflow.
DMC
Duff Moisture Code. Moisture content of loosely compacted organic layers. In BC's rain-shadow interior, DMC rises sharply in summer; coastal stations rarely exceed moderate DMC even in peak season.
DC
Drought Code. Deep organic layer moisture and smoldering potential. BC's high winter precipitation produces significantly lower spring startup DC values than Alberta — particularly on the coast (DC≈50) and interior-wet belt (DC≈75). The Southeast Fire Centre, with dry winters, starts near DC 150–175.
Initial Spread Index
Calculated from FFMC and Wind Speed. Represents potential rate of fire spread independent of fuel quantity. BC's complex terrain creates strong local wind amplification — valley exits, ridgelines, and outflow winds can produce ISI spikes far exceeding ambient conditions.
BUI
Buildup Index. Total available fuel for combustion — a combination of DMC and DC. The most meaningful predictor of fire size and duration in BC's C3 lodgepole pine landscape, where BUI > 80 combined with ISI > 15 historically precedes large-fire days.
FWI
Final numerical rating of fire intensity potential. Combines ISI and BUI. Evaluated against the BC Wildfire Service 5-class danger scale — thresholds are lower than Alberta's to reflect BC's generally wetter conditions and the hazard significance of each class in operational fire management.
Atmospheric Dependencies
BC Wildfire Service Danger Scale — 5 Classes
BC uses five danger classes. "Very High" does not exist in the BC scale — "High" transitions directly to "Extreme" at FWI 34. Thresholds are calibrated to BC climate; the same FWI value implies different operational significance than in Alberta. Source: BC Wildfire Service CFFDRS Implementation Guide (BCWS, 2022).
Fuels are moist. Ignition is very difficult; fires will not spread or can be extinguished with hand tools. BC coastal conditions frequently produce this class year-round.
Fuels do not ignite readily. Fires spread slowly and are easily controlled. Coastal and interior-wet belt stations commonly sit here through June.
Fires start easily from sparks; moderate spread. Control is feasible with initial attack. Interior valleys and the Cariboo typically cross this threshold in late June.
Fire starts readily. Rapid spread in C3/C7 fuels; spotting common. Requires increased initial attack resources. Southeast BC and Kamloops regularly exceed this in July–August.
Blow-up potential. Erratic fire behaviour in C3 lodgepole. Long-range spotting. Direct attack not recommended. The 2017, 2018, and 2023 mega-fire seasons were characterized by sustained Extreme class across multiple Fire Centres.
BC vs Alberta — Why Thresholds Differ
Alberta's scale has six classes including "Very High" (FWI 33–49), with Extreme beginning at FWI 50. BC's Extreme begins at FWI 34 — a critical operational difference. The same FWI reading of 40 is "Very High" in Alberta but "Extreme" in BC. Do not apply Alberta thresholds to BC operational decisions.
BC Scale (this app)
Alberta Scale (AB app)
Source: BC Wildfire Service CFFDRS Implementation Guide (BCWS, 2022); van Wagner, C.E. (1987). Development and Structure of the Canadian Forest Fire Weather Index System. Forestry Technical Report 35.
Fire Behavior Prediction System
ST-X-3 · 1992The FBP System translates FWI outputs and fuel type into operational fire behaviour: Rate of Spread (ROS), Head Fire Intensity (HFI), Crown Fraction Burned (CFB), and flame length. The equations are identical across provinces — only the dominant fuel types differ. In BC, C3 Mature Lodgepole Pine is the default interior fuel; C7 Ponderosa Pine/Douglas-fir dominates the south interior; S3 Cedar/Hemlock/DF Slash is critical in the coastal wet belt post-harvest areas.
Operational Caution — Taylor, Pike & Alexander (1997)
"Fire behavior predictions are intended to assist in decision making, and are not a substitute for experience, sound judgment, or observation of actual fire behavior." ROS predictions are accurate to approximately ±20% for rates > 3 m/min; accuracy decreases for slow-moving fires. Predictions assume flat terrain, open-canopy wind, and homogeneous fuel — adjust for slope, sheltering, and fuel patchiness. BC's complex terrain (valley winds, slope channelling, marine inflow) can produce fire behaviour that significantly exceeds flat-terrain FBP predictions. CFB thresholds: <10% surface fire; 10–89% intermittent crown fire; ≥90% continuous crown fire.
Core Equations (National Standard — identical to Alberta)
Rate of Spread (m/min)
ROS = a × (1 − e−b·ISI)c × BE
where BE = exp(50 · ln(q) · (1/BUI − 1/BUI₀))
Head Fire Intensity (kW/m)
HFI = (H × TFC × ROS) / 60
H = 18,000 kJ/kg; TFC = SFC + (CFB × CFL)
Flame Length (m)
L = 0.0775 × HFI0.46
Byram (1959)
Crown Fraction Burned
CFB = 1 − e−0.23(ROS−RSO)
Van Wagner (1977); RSO = CSI / (H × SFC)
FBP System HFI Intensity Class 1–6 (National Standard)
HFI intensity classes are a national FBP standard — identical for BC and Alberta. Source: Taylor, Pike & Alexander (1997), Special Report 11.
| Class | HFI (kW/m) | Flame Length | Attack Mode |
|---|---|---|---|
| 1 — Low | < 10 | < 0.2 m | Direct attack with hand tools · Should anchor |
| 2 — Moderate | 10 – 500 | 0.2 – 1.5 m | Direct attack with hand tools · Should anchor |
| 3 — High | 500 – 2,000 | 1.5 – 2.5 m | Direct attack with pump and hose · Should anchor |
| 4 — Very High | 2,000 – 4,000 | 2.5 – 3.5 m | Indirect attack; direct attack on less intense area · Must anchor |
| 5 — Extreme | 4,000 – 10,000 | 3.5 – 5.5 m | Indirect attack; direct attack on less intense area · Must anchor |
| 6 — Catastrophic | > 10,000 | > 5.5 m | No direct attack — evacuate structure zone |
Sources: Taylor, Pike & Alexander (1997), Special Report 11 [8]; Forestry Canada Fire Danger Group (1992), ST-X-3 [3].
BC Spring DC Startup & Overwinter Carry-over
BC-Specific · Van Wagner 1985BC spring DC startup values are substantially lower than Alberta's because of higher winter precipitation and snowpack recharge — particularly on the coast and in the interior-wet belt. Alberta's standard startup (DC 300) would overestimate drought severity in coastal and northern BC stations. BC Wildfire Service formally implements Van Wagner's (1985) overwinter DC carry-over algorithm for operational use; this app uses the practical cold-start defaults below as a browser-side fallback.
DC Startup Defaults by Fire Centre — This App
These values are used as cold-start DC when no CWFIS carry-over chain is available. They are moot during fire season when SWOB/NWP provides observed weather and the Van Wagner chain runs forward. Exact station values are in bc/fwi.js → BC_STATION_STARTUP_DC.
Very high winter precip; minimal carry-over. Stations: Campbell River, Comox, Nanaimo, Port Hardy, Tofino, Victoria.
High maritime precip. Coastal stations (Terrace, Prince Rupert) at 50; transitional stations (Smithers, Burns Lake) at 75.
Moderate boreal snowpack; moderate precip. Most stations at DC 100; McBride (wet Columbia trench) at 75.
Interior plateau with moderate precip. 100 Mile House, Horsefly at 100; Williams Lake (drier leeward) at 125.
Rain shadow interior. Revelstoke (wet Columbia) at 75; Kamloops, Lillooet, Williams Lake at 125; others at 100.
Drier inland valleys with lower precipitation. Cranbrook, Invermere at 175; Fernie, Castlegar at 150; Nelson at 125.
Overwinter DC Algorithm — Van Wagner (1985)
BC Wildfire Service operationally applies Van Wagner's overwinter carry-over formula: DC_spring = DC_fall × e(-rw/a) + b, where rw is the total overwinter precipitation (Nov–Mar in mm), and constants a=99.0, b=−91.5 calibrated to BC conditions. This produces a biologically meaningful spring startup from the autumn fire season's final DC value — accounting for wetting from fall and winter precipitation. This app uses simplified regional defaults (above) as a practical browser-side substitute. For operational precision, use BCWS-supplied startup values at the start of each fire season.
Data Sources & Methodology — BC
Full ProvenanceWeather Source — BC Two-Tier Hierarchy
MSC SWOB Realtime (Primary) · Open-Meteo NWP (Fallback) · No API Key
Important: The NRCan CWFIS fire weather station network (firewx_stns_current WFS layer) covers stations east of approximately −114°W — the Alberta boreal and parkland zones. BC is entirely west of −114°W and receives no CWFIS station coverage. BC current conditions therefore use a two-tier hierarchy without a CWFIS primary tier. Tier 1 — MSC SWOB Realtime: real sensor observations from Environment Canada's automated weather station network, available year-round from airports and climate reference stations. Tier 2 — Open-Meteo NWP: ECMWF IFS 0.25° model output at exact station coordinates when SWOB has no coverage within 150 km.
GET api.weather.gc.ca/collections/swob-realtime/items
?bbox={lng-1.5},{lat-1.5},{lng+1.5},{lat+1.5}
&limit=50&f=json
CFFDRS specifies noon Local Standard Time (LST) as the standard daily observation time. For BC (Pacific Standard Time = UTC−8), this is 20:00 UTC year-round. The app targets the 20:00 UTC SWOB observation; if no obs within ±1 hour is found, the most recent observation is used and labelled accordingly. FWI codes are not pre-computed from SWOB — Van Wagner equations are applied live against BC spring startup constants or the last known carry-over.
GET api.open-meteo.com/v1/forecast
?latitude={lat}&longitude={lng}
&hourly=temperature_2m,relative_humidity_2m,wind_speed_10m,wind_direction_10m,precipitation
&forecast_days=1&timezone=UTC
→ select index where UTC hour = 20 (noon PST)
NWP interpolates model grid-point output to the exact station coordinate. Captures synoptic patterns but misses valley inversions, terrain channelling, sea-breeze modulation, and marine influence. Mountain and coastal stations in BC are most affected by NWP limitations. Stations in the Coast Mountains and deep fjords are particularly prone to NWP errors in wind direction and humidity.
GET cwfis.cfs.nrcan.gc.ca/geoserver/public/wfs
?service=WFS&version=2.0.0&request=GetFeature
&typeNames=public:firewx_naefs
&outputFormat=application/json
&CQL_FILTER=code={station_code}&count=20
Unlike the fire weather station network, the NAEFS ensemble forecast layer does cover BC — 35 stations discovered via WFS query (province_state='BC'). Station codes range 10183–10269. Nearest station within 150 km is used by Haversine distance. Returns up to 16 daily forecast records: max_temp, min_rh, median_ws, median_pcp. FWI computed client-side via Van Wagner carry-forward chain from current observed values.
D+1 Peak Burn Prediction — FBAN Operational Product
Fire Behaviour Analyst · 15:00 PDT Planning Window · FBP ST-X-3
The operational FBAN workflow: at approximately 15:00 PDT, the analyst predicts fire behaviour during the next day's peak burn period (~14:00 PDT). This app generates that product automatically on the Forecast page.
Calculation Chain
Step 1 — Today's observed conditions (SWOB or NWP, noon LST) → Van Wagner → FFMC / DMC / DC chain state
Step 2 — Tomorrow's noon forecast (NAEFS max_temp / min_rh / median_ws, or ECMWF hour 12) → carry-forward → D+1 FFMC / DMC / DC
Step 3 — Tomorrow's 14:00 forecast + D+1 FWI codes → calculateFBP(fuelCode, ffmc, dmc, dc, wind_14h)
Step 4 — Outputs: Head ROS (m/min), HFI (kW/m), Flame Length (m), Fire Type, CFB (%)
Station Network — 41 BC Locations by Fire Centre
Search Origins · SWOB + NWP Data Hierarchy · All 6 Fire Centres
Stations in bc/fwi.js → BC_STATIONS[] are nominal search coordinates used to query SWOB and NAEFS. They correspond to established BC Wildfire Service fire weather monitoring locations. Coverage spans 48°N (Victoria) to 58°N (Dease Lake) and the full provincial east–west extent.
Campbell River, Comox, Nanaimo, Port Hardy, Powell River, Squamish, Tofino, Victoria
Chase, Kamloops, Lillooet, Merritt, Penticton, Princeton, Revelstoke, Vernon
100 Mile House, Alexis Creek, Horsefly, Quesnel, Williams Lake
Fort St. James, Mackenzie, McBride, Prince George, Vanderhoof
Burns Lake, Dease Lake, Prince Rupert, Smithers, Terrace
Castlegar, Cranbrook, Fernie, Golden, Invermere, Nelson
Calculation Pipeline — bc/fwi.js
Standalone BC engine · Province hardcoded · No shared state with AB app
Weather inputs (T, RH, W, r) → FFMC → DMC → DC → ISI → BUI → FWI. All six equations implemented verbatim from the Forestry Canada publication. Day-length adjustment factors applied by calendar month.
Spring startup defaults: FFMC = 85, DMC = 6. DC startup is station-specific by Fire Centre — see the DC Startup table above. These cold-start values are used during the off-season or when no SWOB carry-over is available. Danger rating uses the BC 5-class scale — BC scale is hardcoded in bc/fwi.js.
Identical to Alberta implementation — same equations, same fuel type parameters. Default fuel is C3 — Mature Jack/Lodgepole Pine (BC interior dominant) and C7 — Ponderosa Pine/Douglas-fir (BC south interior), replacing Alberta's C2/D1 defaults. Foliar moisture content (FMC) computed seasonally by latitude and DOY per Van Wagner (1987).
bc/fwi.js is a self-contained BC engine. _province is hardcoded to 'BC' — no localStorage province switching, no Alberta code paths. The Alberta app (fwi.js in root) is completely independent. Changes to either engine do not affect the other.
All 16 CFFDRS FBP Fuel Types — ST-X-3 Parameters
Forestry Canada ST-X-3 (1992) · National Standard · User-selectable via fuel picker
The FBP System defines 16 fuel types. Selecting the correct fuel type is the single most impactful decision in a fire behaviour prediction — the same FWI can produce HFI values that differ by 10× across fuel types. Defaults for this app are C3 — Mature Jack/Lodgepole Pine (Fuel A) and C7 — Ponderosa Pine/Douglas-fir (Fuel B). Parameters below are sourced directly from bc/fwi.js → FUEL_TYPES{}.
| Code | Name | a | b | c | q | BUI₀ | CBH m | CFL kg/m² | SFC kg/m² | BC Occurrence |
|---|---|---|---|---|---|---|---|---|---|---|
| Conifer Types | ||||||||||
| C1 | Spruce-Lichen Woodland | 90 | 0.0649 | 4.5 | 0.90 | 72 | 2 | 0.75 | 0.75 | Northern BC, sub-boreal spruce/lichen; NW & PG Fire Centres |
| C2 | Boreal Spruce | 110 | 0.0282 | 1.5 | 0.70 | 64 | 3 | 0.80 | 0.80 | NE BC Peace Country, high-elevation spruce; NW lower elevations |
| C3 ★ | Mature Jack/Lodgepole Pine | 110 | 0.0444 | 3.0 | 0.75 | 62 | 8 | 1.15 | 1.15 | ★ Fuel A default — dominant interior BC fuel: Kamloops, Cariboo, PG, SE |
| C4 | Immature Jack/Lodgepole Pine | 110 | 0.0293 | 1.5 | 0.75 | 66 | 4 | 1.20 | 1.20 | Post-MPB salvage cutblocks, regenerating lodgepole, post-fire stands |
| C5 | Red and White Pine | 30 | 0.0697 | 4.0 | 0.80 | 56 | 18 | 1.20 | 1.20 | Rare in BC; eastern ON/QC type. High CBH = crown fire resistant at lower intensities |
| C6 | Conifer Plantation | 30 | 0.0800 | 3.0 | 0.80 | 62 | 7 | 1.80 | 1.80 | Dense planted stands; highest CFL of all types — extreme crown fire fuel load |
| C7 ★ | Ponderosa Pine / Douglas-fir | 45 | 0.0305 | 2.0 | 0.85 | 106 | 10 | 0.50 | 0.50 | ★ Fuel B default — South Okanagan, Boundary, East Kootenay, S. Kamloops |
| Deciduous Types | ||||||||||
| D1 | Leafless Aspen | 30 | 0.0232 | 1.6 | 0.90 | 32 | 0 | 0.00 | 0.35 | Peace Country, NE BC aspen groves; surface fire only (CBH=0, CFL=0) |
| D2 | Green Aspen | 6 | 0.0232 | 1.6 | 0.90 | 32 | 0 | 0.00 | 0.35 | Very low spread (a=6); green leaf moisture suppresses fire. Summer aspen. |
| Mixedwood Types (Blended ROS) | ||||||||||
| M1 | Boreal Mixedwood — Leafless | ROS = PS% × C2_ROS + (1−PS%) × D1_ROS | NE BC Peace Country mixed boreal; spruce-aspen blends | |||||||
| M2 | Boreal Mixedwood — Green | ROS = PS% × C2_ROS + (1−PS%) × D2_ROS | Same stand as M1 in summer (green hardwood suppresses spread) | |||||||
| Grass Types (Curing-Dependent) | ||||||||||
| O1a | Matted Grass | 190 | 0.031 | 1.4 | 1.00 | 1 | 0 | 0.00 | 0.35 | Thompson/Nicola grasslands, Peace Country; curing % required — see below |
| O1b | Standing Grass | 250 | 0.035 | 1.7 | 1.00 | 1 | 0 | 0.00 | 0.35 | South Okanagan, Boundary; faster spread than O1a; extreme rates at 100% curing |
| Slash Types (Surface Fire — No Crown) | ||||||||||
| S1 | Jack/Lodgepole Pine Slash | 75 | 0.0297 | 1.3 | 0.75 | 38 | 0 | 0.00 | 4.50 | Post-harvest lodgepole cutblocks; extremely high SFC — intense surface fire |
| S2 | White Spruce / Balsam Slash | 40 | 0.0438 | 1.7 | 0.75 | 63 | 0 | 0.00 | 4.50 | Post-harvest spruce/fir cutblocks; same high SFC; slower spread than S1 |
| S3 | Cedar / Hemlock / DF Slash | 55 | 0.0829 | 3.2 | 0.75 | 31 | 0 | 0.00 | 4.50 | Coastal wet belt and interior cedar-hemlock zone post-harvest; very rapid spread at low BUI |
C3 vs C7 — The Two BC Default Fuels
C3 (lodgepole, a=110) and C7 (ponderosa/Douglas-fir, a=45) have very different spread characteristics. C3 reaches near-maximum spread at moderate ISI and has lower CBH (8m vs 10m) — more prone to crown involvement. C7 spreads slower on the surface but has higher BUI₀ (106 vs 62), meaning BUI has a larger effect at high values. In the south Okanagan under Extreme conditions (FWI ≥ 34), C7 with high BUI can produce extreme HFI through fuel quantity rather than spread rate.
M1/M2 — Mixedwood Blending (PS% Parameter)
M1/M2 do not have their own a/b/c coefficients. ROS is a weighted blend: ROS = PS% × ROS_C2 + (1−PS%) × ROS_D1/D2, where PS% is the percent softwood by crown volume (set via the slope/PS picker). At PS=100%, M1 behaves identically to C2. At PS=0%, M1 behaves like D1. The practical range for BC mixed boreal is PS=40–70%. M2 uses D2 (green aspen) for the hardwood component — significantly slower in summer.
O1a/O1b — Grass Curing Controls Spread Rate
For grass types, curing percent is the dominant driver — more influential than wind or FFMC. The FBP system applies a Curing Factor (CF) to modify ISI before evaluating ROS: CF = 0.005 × (e^(0.061×PC) − 1). At 60% curing, CF≈0.19 (marginal spread); at 80%, CF≈0.51; at 100%, CF≈2.22 (ISI amplified 2.2× — extreme rates). O1b (standing grass, a=250) produces faster spread than O1a (matted, a=190). Use the curing slider on the station detail page. South Okanagan grasslands can reach 90–100% curing by August.
S1–S3 — Slash Types Are Surface-Fire Only
All slash types have CBH=0 and CFL=0 — they cannot initiate crown fire. However, SFC=4.50 kg/m² (vs 0.35–1.80 for forest types) means slash fires produce extremely high surface fire intensity and HFI even at moderate spread rates. S3 (cedar/hemlock slash) has the highest spread rate (a=55, c=3.2) and lowest BUI₀ (31) of the slash types — it responds rapidly to even moderate ISI conditions and is particularly dangerous in BC's coastal and interior cedar-hemlock logging areas.
Mountain Pine Beetle — C3 Limitations
Large areas of interior BC lodgepole were killed by MPB (1999–2015), creating standing dead-fuel mosaics. Red-attack stands (recently dead, needles still on) carry far more fine fuel than the C3 green-canopy model assumes. Grey-attack stands (needles fallen) may behave more like C4 or D1. For post-MPB stands, consult BCWS fuel type updates — C4 or M1/M2 may better represent current structure. C3 predictions in heavily affected stands should be treated as conservative estimates for green-canopy conditions.
Primary References
- [1]Van Wagner, C.E. & Pickett, T.L. (1985). Equations and FORTRAN program for the Canadian Forest Fire Weather Index System. Forestry Technical Report 33. Canadian Forestry Service, Ottawa.
- [2]Van Wagner, C.E. (1987). Development and structure of the Canadian Forest Fire Weather Index System. Forestry Technical Report 35. Canadian Forestry Service, Ottawa.
- [3]Forestry Canada Fire Danger Group (1992). Development and structure of the Canadian Forest Fire Behavior Prediction System. Information Report ST-X-3. Forestry Canada, Ottawa.
- [4]Van Wagner, C.E. (1977). Conditions for the start and spread of crown fire. Canadian Journal of Forest Research, 7(1), 23–34.
- [5]Van Wagner, C.E. (1985). Drought, timelag and fire danger rating. In Proceedings 8th Conference on Fire and Forest Meteorology. pp. 178–185. Society of American Foresters, Bethesda, MD. — Overwinter DC carry-over algorithm used by BCWS.
- [6]BC Wildfire Service (2022). CFFDRS Implementation Guide — BC Danger Scale and Operational Application. BC Ministry of Forests. — Defines BC 5-class danger scale (Very Low/Low/Moderate/High/Extreme) and FWI thresholds.
- [7]Byram, G.M. (1959). Combustion of forest fuels. In K.P. Davis (Ed.), Forest Fire: Control and Use (pp. 61–89). McGraw-Hill.
- [8]Taylor, S.W.; Pike, R.G.; Alexander, M.E. (1997). Field Guide to the Canadian Forest Fire Behavior Prediction (FBP) System. Special Report 11. Natural Resources Canada, Northern Forestry Centre, Edmonton, AB.
- [9]Environment and Climate Change Canada / NOAA (2003–present). North American Ensemble Forecast System (NAEFS). Distributed via NRCan CWFIS WFS layer public:firewx_naefs. BC stations: codes 10183–10269 (35 stations, discovered via WFS query province_state='BC').
Operational Limitations — BC
Read Before Use in Operations
- ▸No CWFIS fire weather station coverage: BC is west of −114°W; the NRCan
firewx_stns_currentWFS layer does not return BC stations. All BC current conditions come from SWOB or NWP — the pre-computed NRCan FWI carry-over chain is not available for BC stations in this app. - ▸SWOB — no pre-computed FWI: Unlike CWFIS in Alberta, SWOB returns raw weather observations only. Van Wagner equations are applied client-side using BC spring startup constants. Off-season DC may be systematically underestimated.
- ▸DC divergence warning: DC has a ~53-day e-folding memory of accumulated precipitation and cannot be meaningfully averaged between stations that experienced different rainfall. When ≥2 CWFIS stations within 75 km differ by ≥75 DC units, the app shows an amber warning. This indicates a localised precipitation event may have created a step-change in DC across the landscape. The operator should review nearby station DCs and select the station whose precipitation history best represents the target fuel complex.
- ▸Terrain effects — BC is complex: Chinook-like valley outflow, sea breezes, mountain gaps, and strong diurnal cycles in BC's coastal and interior terrain produce fire weather that NWP models poorly resolve at 0.25°. For stations in the Coast Range, Columbia Mountains, and Cascade foothills, treat NWP-sourced FWI values with greater caution than equivalent Alberta results.
- ▸BC danger scale — do not apply Alberta thresholds: An FWI of 35 is "Extreme" in BC but "Very High" in Alberta. Always confirm which province's scale is in use. This app hardcodes the BC scale in
bc/fwi.js. - ▸Mountain Pine Beetle fuel modification: Large areas of interior lodgepole have been structurally altered by MPB. C3 default may overpredict canopy fire intensity in grey-attack (defoliated) stands or underpredict in red-attack (fully loaded) stands. Use local BCWS fuel type mapping when available.
- ▸No slope aspect: FBP slope factor = 0% for all stations. Mountain terrain in BC (Coast Mountains, Rockies, Columbia/Purcell/Selkirk ranges) is particularly affected. Actual HFI on steep slopes may be 2× or more above the flat-terrain prediction.
- ▸Situational awareness only: Suppression resource decisions require certified BCWS weather station observations and interpretation by a qualified Fire Behaviour Analyst (FBA) holding a BC Wildfire Service credential.
Reading the Live Map
Bicolor pill markers · Cluster bubbles · Popup detail
Bicolor Pill Markers
Each station is shown as a split pill. The left half encodes the FWI Danger class; the right half encodes the HFI Byram intensity class. Both indices can differ for the same observation — a dry but calm day may have High FWI but only Moderate HFI, while a windy day in dense fuel may show both extreme.
Left Half — FWI Danger
Right Half — HFI Byram Class
Marker Shape — Data Source
Cluster Bubble
At provincial zoom (≤ 6), stations too close to display separately collapse into a dark-blue numbered circle. The number is the station count. Click to spiderfy and see individual pills. Clustering dissolves automatically at zoom 7+.
Loading State
A gray … pill means the data fetch for that station is still in progress. All BC stations load concurrently; most resolve within 2–4 seconds. If a station stays gray, it failed silently and its popup will show no data.
Zoom & Size
Pills scale with zoom: small at provincial (zoom ≤ 5), medium at regional (zoom 6–7), large at municipal (zoom ≥ 8). Labels for FWI value and HFI class word become readable at medium and large sizes.
Station Popup
Click any pill to open a detail popup. It shows: the zone name and the actual source station name, coordinates and km offset from the zone search origin, the data tier badge (BCWS / CWFIS / SWOB / NWP), the observation timestamp, and the full FWI + HFI grid. When FWI was calculated using Van Wagner equations (CWFIS/SWOB/NWP tier), a Carry-over line shows the BCWS or CWFIS station and date whose FFMC/DMC/DC values seeded the calculation.
STANDARDS
About Pyra
Pyra is an open-source wildfire weather tool built for operational use by wildland firefighters, fire behaviour analysts, and emergency managers. It integrates live fire weather observations from the Canadian Wildland Fire Information System (CWFIS) with NRCan's Canadian Forest Fire Danger Rating System (CFFDRS) — combining real-time FWI codes from the operational carry-over chain with FBP System fire behaviour predictions across standard fuel types. Weather data flows through a three-tier hierarchy: CWFIS fire weather stations (pre-computed FWI chain), MSC SWOB real-sensor observations, and ECMWF IFS numerical forecast as a last resort. Station coverage includes British Columbia (260+ stations grouped by Fire Centre) and Alberta (39 stations). Built by Travis Kennedy, Claude, and Glenn. Free, open, no login required.