Wildfire Spread Simulator
Drop an ignition point and watch a wind-driven fire front and ember cast race toward a home in real time. Run it on any address and it pulls the real LANDFIRE surface fuel and runs the Rothermel equations — the same fire-spread math used in wildland fire science.
⚠️ Educational illustration — never rely on this for safety
This is not a prediction of any real fire and not an evacuation tool. It is a simplified physics model that cannot account for real fuels, suppression, spotting, or minute-to-minute weather, and modeled spread times, directions, and ember reach are illustrative only. Never make any evacuation, safety, or property decision based on this simulation. For real-time fire information and evacuation orders, follow Watch Duty and your local authorities — and call 911 in an emergency.
🏠 Run it on your own home
Centers the simulator on your rooftop with live NWS wind, your USGS terrain slope, and your FireRisk level.
🔥 Simulate the top 100 historic fires
Fuel / risk intensity
Set the wind and slope in the controls, press play, and tap anywhere on the map to move the ignition point. Higher intensity = drier fuels and a faster front.
Loading the simulator…
How the simulator works
Five forces decide where a wildfire goes. The simulator models each one so you can feel how they combine.
Wind-driven elliptical front
Fire doesn’t spread in a circle — wind stretches it into an ellipse, fast at the head and slow at the flanks. The simulator uses Anderson’s (1983) length-to-breadth ratio, the same geometry wildland models use, to shape the front from your wind speed.
Real wind, or yours
It defaults to the live wind direction and speed from the nearest NWS station, then lets you override both. Wind is the single biggest driver of how fast and where a fire moves.
Slope acceleration
Fire moves faster uphill — roughly doubling its rate of spread for every ~10° of upslope. Add slope and an uphill direction and the head vector bends and speeds up accordingly.
Real LANDFIRE fuels + Rothermel
When you run it on a real address or fire, it pulls the actual surface fuel model at that spot from LANDFIRE and runs it through the Rothermel (1972) spread equations with a Byram flame length — the same math behind BehavePlus. Timber, brush, and grass each behave differently; the intensity selector shifts how dry the fuels are.
Ember cast (spotting)
Most homes ignite from wind-blown embers, not the flame front. The simulator throws a downwind ember plume that grows with wind and intensity — often landing well ahead of the fire itself.
Time-to-reach
From the ignition point you place, it estimates roughly how long the flame front would take to reach the home at the modeled rate of spread — shown as a range — and flags that wind-blown embers can arrive well before the front. A visceral sense of how little warning a fast fire gives.
What the model is built on
This is a transparent, physics-informed illustration — not a black box. It draws on established wildland-fire science and live weather data:
What’s growing around you — LANDFIRE fuels
Fire needs something to burn — grass, brush, timber, or logging slash. We read the actual vegetation at your spot from the U.S. government’s LANDFIRE map (its “fuel model”), sampling the wildland around a home, since that’s what would carry a fire toward it. A grass fire and a timber fire behave very differently, and this is how the model knows which you have.
How fast it moves — Rothermel (1972) + Byram (1959)
These are the published equations the U.S. Forest Service and the federal BehavePlus tool use to turn fuel, wind, slope, and dryness into a real rate of spread, flame length, and fire intensity. It’s established fire science, not a guess or an animation.
Whether it reaches the treetops & throws embers — Van Wagner (1977)
Using the height and density of the tree canopy at your location, the model judges whether a fire on the ground would climb into the treetops (a “crown fire”) and how far burning embers could blow ahead of it — which is how most homes actually catch fire.
The shape of the fire — Anderson (1983)
Wind doesn’t push fire out in a neat circle; it stretches it into a long teardrop that races downwind and creeps along the sides. This is the geometry wildland fire models use to draw that advancing front.
Today’s conditions — NWS, USGS & live weather
Live wind from the National Weather Service, the current temperature and humidity (which set how dry the fuels are), and the steepness of your land from USGS elevation all feed the model — because fire runs faster in wind, in dry air, and uphill.
Want the full model, every equation, data source, verification, and limitation? Read how the simulator works.
How fast does a wildfire spread? Typical rates
Wildfire spread rate depends mostly on fuel, wind, and slope. The simulator computes it for your exact location; the ranges below are illustrative, order-of-magnitude figures from the Rothermel surface-fire model for a strong wind (~20–30 mph). Actual fire behavior varies widely — these are educational, not a forecast.
| Fuel type | Head rate of spread | Flame length | Ember spotting |
|---|---|---|---|
| Grass / open range | 2–5 mph (can exceed a mile in 15–20 min) | 5–15 ft | up to ~0.25 mi |
| Brush / chaparral | 1–3 mph | 15–30 ft | ~0.25–1 mi |
| Timber & forest litter | 0.2–0.7 mph (surface) | 2–6 ft | short range unless it crowns |
| Crown fire (into the canopy) | can match or exceed surface runs | 50+ ft | often 0.5–1+ mi ahead of the front |
Embers (firebrands) routinely ignite homes well ahead of the flame front — which is why the simulator shows ember cast separately, and why defensible space and home hardening matter even when the fire looks far away.
Wildfire spread simulator — FAQ
What is a wildfire spread simulator?
A wildfire spread simulator is an interactive model that shows how a fire would move across the landscape given conditions like wind, slope, and fuel. You place an ignition point and the tool projects the fire front and wind-blown embers over time. This one is designed to make the physics intuitive — how wind stretches a fire into a fast-moving ellipse, how slope accelerates it uphill, and how embers leap ahead of the flames — rather than to predict a specific real-world fire.
How does the wildfire spread simulator work?
On a real address it pulls the LANDFIRE surface fuel at that spot and runs the Rothermel (1972) equations with a Byram (1959) flame length, driven by live NWS wind, your USGS terrain slope, and current temperature/humidity (which set the dead-fuel moisture); a Van Wagner (1977) check flags potential crown fire and ember spotting, and Anderson’s (1983) length-to-breadth ratio gives the front its wind-driven elliptical shape. From those it computes a head rate of spread and direction, draws the advancing front, casts a downwind ember plume, and estimates how long the front and embers would take to reach the home from the ignition point you choose.
Is this an accurate wildfire prediction?
No — and it’s important to be clear about that. It is an educational illustration of how fire and embers tend to behave, not an operational forecast. Real fire behavior depends on fuel moisture, fuel type and continuity, micro-terrain, suppression, and weather that change minute to minute. For real-time fire information and evacuation orders, always follow local authorities, InciWeb, and your state emergency agencies.
Why do the embers travel farther than the fire?
Because that’s what actually destroys most homes. In a wind-driven wildfire, burning embers (firebrands) are lofted and carried far downwind — sometimes more than a mile ahead of the flame front — landing in gutters, vents, and on decks. The simulator shows this ember cast separately from the front to make the point that defensible space and home hardening matter even when the visible fire is still far away.
Can I simulate a fire near my own home?
Yes — use the “Run it on your own home” box at the top of the simulator. Enter your address and it centers the model on your rooftop, then pulls your live wind from the nearest NWS station, your terrain slope from USGS elevation, and your FireRisk level — so the fire behaves the way it would on your actual property. You can also pick a well-known wildfire location to explore. For your full wildfire risk score, insurance exposure, and the mitigation that lowers it, run a free FireRisk report on your home.
See how fire could reach your home
Run a free FireRisk report and get the simulator centered on your exact address — plus your 0–100 wildfire risk score, insurance exposure, and the mitigation that lowers it.
Check my home’s wildfire risk score →Educational illustration only. This wildfire spread simulator is a simplified model of fire behavior and is not an operational forecast, evacuation tool, or prediction of any real fire. Actual fire behavior depends on fuels, moisture, terrain, suppression, and rapidly changing weather. In a wildfire, follow local authorities, InciWeb, and official emergency alerts. Live wind via NWS/NOAA; model based on Rothermel (1972), Byram (1959), Van Wagner (1977), and Anderson (1983) on LANDFIRE fuels.