Wildfires burned over 28 million acres in the United States alone between 2020 and 2024, causing tens of billions in property damage and disrupting supply chains across multiple industries. A wildfire risk assessment evaluates the likelihood and potential severity of wildfire at a specific location by analyzing temperature patterns, vegetation, terrain, and climate projections. Organizations use these assessments to screen real estate, evaluate insurance exposure, and meet TCFD disclosure requirements.
Understanding how wildfire risk assessment works helps risk managers move beyond historical fire perimeters and into forward-looking, climate-informed analysis that accounts for how warming changes fire weather patterns.
What Is Wildfire Risk Assessment?
Wildfire risk assessment is the process of evaluating how likely a location is to experience wildfire and how severe that fire could be. It combines climate data, land cover analysis, and terrain characteristics to produce a risk rating that reflects both current conditions and projected changes under climate warming scenarios.
Unlike structural fire risk assessment, which focuses on building codes and fire suppression systems, wildfire risk assessment evaluates landscape-level conditions. The core question is whether the combination of weather, fuel, and terrain at a given location creates conditions where wildfire can ignite and spread.
Modern wildfire risk assessments incorporate climate model projections from CMIP6 to estimate how fire weather conditions will change through 2030, 2040, and 2050. As temperatures rise, the number of days with conditions favorable for wildfire increases in most regions, making forward-looking assessment essential for any organization with assets in fire-prone areas.
Key Factors in Wildfire Risk
Wildfire risk assessment depends on five primary factors that determine whether fire can start, sustain, and spread at a given location. Each factor contributes independently, and the combination determines overall risk.
Temperature. Maximum daily temperature is the strongest predictor of fire weather. Higher temperatures dry out vegetation, lower fuel moisture content, and increase the probability of ignition. Locations where mean daily maximum temperatures exceed 30 degrees Celsius face significantly elevated wildfire risk assessment scores.
Wind speed. Surface wind accelerates fire spread, carries burning embers across firebreaks, and makes suppression more difficult. Wind-driven fires are responsible for the most destructive wildfire events, including many of the fires that have devastated communities in California, Australia, and southern Europe.
Fuel availability. Vegetation type and density determine how much combustible material exists. Forests, grasslands, and shrublands provide high fuel loads. The condition of that fuel matters too: drought-stressed vegetation ignites more easily and burns more intensely than healthy, well-watered plants.
Humidity. Low relative humidity dries fuels faster and allows fires to burn more intensely. Extended periods of low humidity, combined with high temperatures, create the critical fire weather conditions that drive the most severe wildfire events.
Land cover type. Not all land is equally susceptible to wildfire. Forested and vegetated areas carry the highest risk. Bare ground, water bodies, permanent snow and ice, and built-up urban areas are classified as low susceptibility in wildfire risk assessment models because they lack the fuel needed to sustain fire spread.
How Wildfire Risk Is Scored
Wildfire risk assessment scoring translates raw climate and land cover data into actionable risk ratings. The primary metric is fire weather days per year: the number of days where temperature and atmospheric conditions are conducive to wildfire ignition and spread.
Scoring uses a piecewise approach based on mean daily maximum temperature (tasmax). Locations where mean tasmax stays below 20 degrees Celsius receive zero fire weather days. Between 20 and 25 degrees, a baseline of 2 fire weather days is assigned. Above 25 degrees, the relationship becomes steeper: each additional degree adds progressively more fire days.
At mean tasmax above 35 degrees Celsius, fire weather days accumulate rapidly, reaching up to 120 days per year in the most extreme cases. The scoring reflects real-world observations that wildfire risk increases nonlinearly with temperature.
| Risk Rating | Fire Weather Days per Year |
|---|---|
| Low | Fewer than 5 |
| Moderate | 5 to 15 |
| High | 15 to 30 |
| Severe | 30 to 45 |
| Extreme | More than 45 |
Land cover acts as a filter on top of the temperature-based score. Locations classified as bare ground, water, permanent snow or ice, or built-up areas automatically receive a Low rating regardless of temperature, because these surfaces lack the fuel needed to sustain wildfire. ESA WorldCover data at 10-meter resolution provides the land cover classification used in this step.
Wildfire Risk and Climate Change
Climate change is expanding the geographic range, season length, and intensity of wildfires globally. Warmer temperatures dry fuels faster, extend fire seasons, and push fire-prone conditions into regions that historically experienced few wildfires.
Under SSP5-8.5 (high emissions), mean maximum temperatures are projected to increase by 2 to 4 degrees Celsius in many mid-latitude regions by 2050. Because the fire weather day formula is nonlinear, even a 2-degree increase can double the number of fire weather days at locations already near the threshold.
Regions experiencing the fastest growth in wildfire risk include the Mediterranean basin, western North America, central Asia, and southern Australia. However, warming is also increasing wildfire risk assessment scores in areas not traditionally considered fire-prone, such as northern Europe, the Canadian boreal forest, and parts of Siberia where permafrost thaw is exposing new fuel sources.
For a broader view of how warming drives multiple climate hazards simultaneously, wildfire often compounds with drought and heat stress to create cascading impacts across supply chains and infrastructure.
Wildfire Risk Data Sources
Accurate wildfire risk assessment requires data from several sources that cover different aspects of fire behavior.
| Data Source | Coverage | Best For |
|---|---|---|
| NASA NEX-GDDP-CMIP6 | Global, ~25 km | Temperature and wind projections under SSP scenarios |
| ESA WorldCover v200 | Global, 10 m | Land cover classification for fuel susceptibility |
| NIFC | United States | Historical fire perimeters, acreage, and suppression data |
| CAL FIRE | California | Fire hazard severity zones, historical fire data |
| IPCC AR6 | Global | Fire weather attribution, climate-wildfire linkages |
For organizations screening wildfire risk across hundreds of locations globally, platforms that combine these data sources into a single climate risk assessment reduce the complexity of sourcing, processing, and interpreting raw datasets.
Assessing Wildfire Risk for Property and Infrastructure
Wildfire risk assessment for physical assets follows a structured approach that combines the climate and land cover data described above with location-specific analysis.
Step 1: Determine land cover. Query ESA WorldCover at the asset coordinates to classify the surrounding land. If the location falls on water, bare ground, snow, or built-up area, wildfire risk is automatically Low. For vegetated areas, proceed to climate analysis.
Step 2: Pull temperature projections. Extract mean daily maximum temperature (tasmax) from CMIP6 projections for the location under both SSP2-4.5 and SSP5-8.5 scenarios across baseline, 2030, 2040, and 2050 time horizons.
Step 3: Calculate fire weather days. Apply the piecewise scoring formula to convert temperature projections into fire weather day estimates for each scenario and time horizon.
Step 4: Rate and compare. Map fire weather days to risk ratings (Low through Extreme) and compare across scenarios. Locations where risk shifts from Moderate to Severe or Extreme under high emissions are priority candidates for adaptation planning.
Continuuiti’s climate risk platform automates this workflow across all 12 physical climate risk hazards, including wildfire, for any location globally.
Frequently Asked Questions
What is a wildfire risk assessment?
A wildfire risk assessment evaluates the likelihood and potential severity of wildfire at a specific location. It analyzes temperature patterns, wind conditions, fuel availability, humidity, and land cover type to produce a risk rating. Modern assessments include climate projections to estimate how wildfire risk changes under different emission scenarios through 2050.
What are the 5 main components of a fire risk assessment?
The five main components of wildfire risk assessment are: (1) temperature, which drives fuel drying and ignition probability; (2) wind speed, which controls fire spread rate; (3) fuel availability from vegetation type and density; (4) humidity, which affects fuel moisture content; and (5) land cover classification, which determines whether the landscape can sustain fire.
What are the risk factors for wildfires?
Key wildfire risk factors include high maximum temperatures, low humidity, strong winds, dense vegetation (fuel), and dry conditions from drought. Climate change is intensifying these factors by raising baseline temperatures, extending fire seasons, and drying fuels faster. Terrain also plays a role, as fire spreads faster uphill.
How are wildfires measured and classified?
Wildfires are measured by area burned (acres or hectares), fire weather days (days per year with conditions favorable for fire), and fire intensity. Risk classification uses fire weather day thresholds: Low (fewer than 5 days), Moderate (5-15), High (15-30), Severe (30-45), and Extreme (more than 45 days per year).
How does climate change affect wildfire risk?
Climate change increases wildfire risk by raising temperatures, which dries fuels faster and extends fire seasons. Under high-emission scenarios, a 2-degree temperature increase can double fire weather days in regions already near the threshold. Warming is also expanding wildfire risk into regions not traditionally considered fire-prone, such as northern Europe and the Canadian boreal forest.
Conclusion
Wildfire risk assessment combines temperature projections, land cover data, and fire weather modeling to quantify fire exposure at any location. With climate change pushing fire weather conditions into new regions and extending fire seasons globally, forward-looking wildfire risk assessment is essential for protecting assets, meeting disclosure requirements, and making informed decisions about where to build, insure, and invest.
