Information compiled by Leandro Gonzalez

Other Names

Fire Area Simulator


FARSITE is a fire growth simulation modeling system. The system utilizes spatial data related to topography and fuels, as well as weather and wind information. FARSITE incorporates predefined models for surface fire, crown fire, spotting, post-frontal combustion, and fire acceleration to produce a 2-D fire growth model. The U.S. Forest Service and National Park Service, as well as various other federal and state land management agencies, commonly use FARSITE. The model simulates the dispersion and distribution of wildfires and fire use for resource benefits across the landscape. Due to the complexity of the model, only users with the adequate fire behavior knowledge, training, and expertise should use FARSITE if the outputs are to be used fire and land management decisions. FARSITE is a deterministic modeling system, meaning that simulation results can be directly compared to inputs. This system can be used to simulate air and ground suppression actions as well as for fire “gaming,” asking multiple “what-if” questions and comparing the results.

Spatial, Tabular Data, and Models

Farsite uses the following data types:

  • Landscape (.LCP) file
  • Initial Fuel Moistures (.FMS) file
  • Custom Fuel Model (.FMD) files (optional)
  • Conversion (.CNV) files (optional)
  • Weather (.WTR) files (optional)
  • Wind (.WND) files (optional)

Farsite uses the following fire behavior models:

  • Rothermel’s (1972) surface fire spread model,
  • Van Wagner’s (1977) crown fire initiation model,
  • Rothermel’s (1991) crown fire spread model, and
  • Nelson’s (2000) dead fuel moisture model.

Software/Hardware Requirements

FARSITE runs under Microsoft Windows operating systems and features a graphical user interface. Users must have the support of a geographic information system (GIS) to use FARSITE since it requires spatial coincident landscape raster information to run.
System Requirements The system is math and data intensive. The hardware selection will influence its performance time. FARSITE v4.1x is multi-threaded, meaning that it will take advantage of multiple processors. Computer systems for running FARSITE v4.1x are listed below in Minimum, Recommended, and Performance categories. Windows 95 no longer supports FARSITE v4.02 or later versions. Advances in computer technology will alter these every year, with performance systems always at the very top end of available hardware. The major criteria in choosing a system are:

  • User’s requirements in terms of the size, complexity, and duration of simulations, such as simulating crown fires, post-frontal combustion, large, or long duration fires
  • User’s need for obtaining the results quickly
  • The degree to which the system can be dedicated to fire simulation (versus less intensive applications).

BehavePlus, FlamMap, and FSPro

FARSITE is part of a set of fire behavior systems. The other systems are: BehavePlus, FlamMap, and FSPro. These are complementary systems that are based on essentially the same fire models. BehavePlus is a point system with input supplied interactively by the user. FlamMap, FARSITE, and FSPro are spatial systems that use the same base GIS data.

FARSITE fire area simulator:

  • Adds the temporal component.
  • Conditions vary in both time and space.
  • Fire growth simulation.
  • The fire behavior at a pixel depends on the adjoining pixels and the time it burned.

BehavePlus fire modeling system

  • Can be considered a ‘point’ system.
  • Each calculation is for a set of uniform conditions.
  • Rarely is a single calculation done.
  • The user looks at the effect of a range of values on the results.
  • Input data are entered by the user. GIS data are not used.
  • Results are in the form of tables, graphs, and simple diagrams.

FlamMap fire mapping and analysis system

  • Adds the spatial component.
  • Point calculations are done for each pixel.
  • Conditions are constant in time, but vary in space.
  • Minimum travel time and other options are also available in FlamMap.
  • Used to examine potential fire behavior across the landscape.

FSPro fire spread probability

  • Probability of fire spread from a known perimeter or point.
  • Not a fire perimeter like FARSITE.
  • Not a projection of fire size.
  • Results are based on thousands of FARSITE simulations for simulated weather sequences.
  • FSPro modeling requires computing power beyond that available on a personal computer.

Input Data Requirements

FARSITE uses spatial and tabular data, including a Landscape (.LCP) file, Initial Fuel Moistures (.FMS) file, as well as optional Custom Fuel Model (.FMD), Conversion (.CNV), Weather (.WTR), and Wind (.WND) files. Raster map layers are required for:

  • Elevation
  • Slope
  • Aspect
  • Surface fuel model (1-13 or custom)

Canopy cover Optional raster themes for simulating spotting and crown fire include:

  • Canopy height
  • Crown base height

Crown bulk density Optional raster themes for simulating post-frontal combustion are:

  • Coarse woody fuels
  • Duff loading


FARSITE is a spatial fire modeling system that produces outputs that are compatible with PC and Workstation graphics and GIS software for later analysis and display. It accepts both GRASS and ARC/INFO GIS raster data themes.


Farsite software can be downloaded for free from the following link. http://www.firemodels.org/index.php/farsite-software/farsite-downloads


The link below offers various Farsite training exercises. http://www.firemodels.org/index.php/farsite-support/farsite-training

Rangeland Use Examples

Miller and Yool. 2002. Evaluated the sensitivity of the fire model FARSITE to the level of detail in the fuels data, both spatially and quantitatively, to better understand requirements for mapping fuels to produce accurate fire simulations.

Paz et al. 2011. Conducted a study of fire risk between 2007 and 2009 utilizing a combination of Monte Carlo simulation of spatial spread of fire ignition with fire behavior model (FARSITE).

Roth et al. 2011. Used custom fuel models and a recent vegetation map processed in FARSITE under moderate fire conditions to create a fire-occurrence grid in three sixth-order watersheds on the Owyhee Plateau of southwestern Idaho.

Rangeland Studies References

Miller J and Yool SR. 2002. Modeling Fire in Semi-desert Grassland/Oak Woodland: the Spatial Implications. In Ecological Modeling. 153(3): 229-245.

Paz S, Carmel Y, Jahshan F, and Shoshany M. 2011. Post-fire analysis of pre-fire mapping of fire risk: A recent case study from Mt. Carmel (Israel). In Forest Ecology and Management. 262(7): 1184-1188.

Roth AD, Bunting SC, and Strand EK. 2011. Relationships between landscape patterns and fire occurrence within a successional gradient in sagebrush steppe-juniper woodland. In International Journal of Wildland Fire. 20(1): 69-77.

Technical References

Missoula Fire Sciences Laboratories. http://www.firemodels.org/index.php/national-systems/farsite

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