Data Sources & Methodology

Understanding how we generate wildfire risk assessments

WildSafe Defense wildfire risk reports combine publicly available data, third-party environmental datasets, and proprietary analysis to provide informational assessments of wildfire risk for California properties.

Important: These reports are informational only and are NOT certified fire engineering assessments. See our Wildfire Risk Report Disclaimer for full limitations.

Primary Data Sources

1. CAL FIRE Fire Hazard Severity Zones (FHSZ)

Official fire hazard zone classifications from the California Department of Forestry and Fire Protection (CAL FIRE), which are the legal basis for wildfire hazard identification in California:

  • State Responsibility Area (SRA) zones: Areas where CAL FIRE has primary firefighting responsibility
  • Local Responsibility Area (LRA) zones: Areas where local fire departments have primary responsibility
  • Federal Responsibility Area (FRA) zones: Federal lands where federal agencies have firefighting jurisdiction
  • Severity Classifications: Very High, High, and Moderate fire hazard severity ratings. FHSZ maps are updated periodically by CAL FIRE and reflect an assessment of fuels, terrain, weather patterns, and other factors.

2. Parcel Boundaries and Property Data

Property parcel data from county assessor offices and public GIS databases to accurately identify specific property locations and boundaries. This data includes:

  • Parcel geometry and boundaries
  • Assessor Parcel Number (APN)
  • Property address and location
  • Lot size and acreage

3. Vegetation and Fuel Data

Vegetation indices and fuel load data from multiple authoritative sources:

  • LANDFIRE: Landscape Fire and Resource Management Planning Tools vegetation and fuel datasets
  • Satellite Imagery: Normalized Difference Vegetation Index (NDVI) derived from Landsat and Sentinel satellites
  • California Vegetation Mapping: CalVeg and other state vegetation classification programs
  • Fuel Moisture: Live and dead fuel moisture estimates where available

4. Topography and Terrain Data

Terrain analysis is critical for understanding fire behavior, as fire spreads faster uphill. We use:

  • USGS Digital Elevation Models (DEMs): High-resolution elevation data
  • Slope Analysis: Slope angle and steepness calculations
  • Aspect: Directional orientation of slopes (south-facing slopes are generally drier)
  • Terrain Features: Ridge and valley identification for fire spread modeling

5. Historical Fire Data

Past wildfire perimeters and burn severity from CAL FIRE, USGS, and federal agencies to understand historical fire patterns:

  • Historical fire perimeters and boundaries
  • Fire occurrence frequency by region
  • Burn severity and fire intensity data
  • Time since last fire in surrounding areas

6. Weather and Climate Data

Long-term weather patterns and climate data that influence wildfire risk:

  • Average wind patterns and prevailing wind directions
  • Precipitation trends and seasonal patterns
  • Temperature extremes and heat wave frequency
  • Drought indices (Palmer Drought Severity Index, etc.)
  • Red Flag Warning and fire weather event history

Risk Scoring Methodology

Our proprietary risk scoring model combines multiple data layers to generate a composite wildfire risk score for each property. The model weighs and integrates the following factor categories:

Environmental Factors

  • • Fuel load, vegetation type, and vegetation density
  • • Terrain steepness, slope, and aspect
  • • Official Fire Hazard Severity Zone classification
  • • Historical fire occurrence in the surrounding region

Location-Specific Factors

  • • Distance to recent fires and fire perimeters
  • • Proximity to Wildland-Urban Interface (WUI)
  • • Access and evacuation route considerations
  • • Regional climate and weather patterns

Model Limitations

Our risk model has inherent limitations that users should understand:

  • Based on static data snapshots and does not reflect real-time conditions
  • Does not account for current wind, humidity, temperature, or active fires
  • Does not evaluate property-specific characteristics (building materials, roof type, vents, defensible space implementation)
  • Cannot predict fire ignition locations or human-caused fires
  • Does not assess emergency response capabilities or fire suppression resources
  • Wildfire behavior is inherently dynamic and influenced by numerous factors beyond any assessment's scope

Report Generation Process

Our reports are generated through the following automated process:

  1. 1

    Property Location Identification

    The provided address is geocoded and matched to parcel boundaries using county assessor data and geospatial databases.

  2. 2

    Data Layer Overlay

    Multiple geospatial datasets are overlaid on the property location to extract relevant environmental, hazard, and contextual information.

  3. 3

    Risk Calculation

    Proprietary algorithms process the data layers to generate composite risk scores based on weighted factors and validated models.

  4. 4

    Report Assembly

    Risk scores, maps, contextual data, and property-specific information are compiled into a comprehensive informational report available in both web-based and downloadable PDF formats.

Data Currency and Updates

We strive to use the most current data available, but data currency varies by source:

  • CAL FIRE FHSZ maps are updated periodically by the state
  • Satellite imagery and vegetation data are typically updated seasonally or annually
  • Parcel data is updated as counties publish new assessor information
  • Historical fire data is updated as new fire perimeters are finalized

Questions or Feedback

For questions about our methodology, data sources, or report generation process, please contact us at support@wildsafedefense.com.