Jason Runnells.

Wildfire Data Profile of California's Mountain Communities

A spatial summary of wildfire threat classifications, fire events, and burn areas from 1950-2024

Jason Runnells | March, 2025

Overview

This project profiles California’s mountain communities by identifying census-designated places (CDPs) located within mountainous terrain and analyzing their surrounding wildfire history and modeled fire threat conditions. By combining geographic context with historical fire perimeters and fire threat data, the goal is not to rank risk, but to provide meaningful wildfire-related statistics that can support awareness, preparedness, and planning efforts for these mountain communities.

Questions

Mountain Communities

To identify mountain communities in California, census-designated places (CDPs) were analyzed based on their topographic characteristics. Each CDP was evaluated to determine whether at least 50% of its area exceeded 1,000 meters in elevation and had an average slope greater than 10 degrees. This filtering process isolated 71 CDPs that meet the criteria, focusing the analysis on settlements situated in elevated, rugged terrain typically associated with mountain environments.


Slope & Elevation Mask

The elevation and slope mask was developed using data from NASA’s Shuttle Radar Topography Mission (SRTM) at 1 arc-second resolution. A raster analysis was performed to extract areas where both elevation exceeds 1,000 meters and slope is greater than 10 degrees. The resulting binary mask highlights regions of significant relief and was used as the spatial filter to assess which CDPs qualify as mountain communities.

Slope & Elevation Mask

Fire Threat Classification

To evaluate current fire exposure conditions, CalFire’s Fire Threat Classification raster (2019) was used to assess modeled wildfire hazard across each of the 71 identified mountain communities. Zonal statistics were applied to extract the dominant threat level within each community boundary, along with the percentage of area it represents. While threat levels range from Low to Extreme, nearly all mountain communities intersect zones classified as Moderate or higher, indicating widespread exposure to potential wildfire risk.


Threat Classification Map

The map displays CalFire’s statewide threat model, which classifies land into five categories: Low, Moderate, High, Very High, and Extreme fire threat. These classifications are based on factors such as fuel type, topography, and historical fire behavior. Areas in red and purple represent the highest levels of modeled fire hazard, often concentrated along mountainous regions with dense vegetation and steep slopes. This backdrop provides spatial context for understanding how mountain communities align with broader statewide fire risk patterns.

Threat Classification Map

Wildfire History

Wildfire activity near the selected mountain communities was assessed using CalFire’s historical perimeter data from 1950 to 2024. A 5-mile buffer was applied around each community to capture nearby fire events and calculate total burn area and fire count within that range. The map below displays the intersecting extent of the available historic wildfire data, the 5-mile buffers around each community, and corresponding statistics.


Statistics

Total Fires

This chart ranks the ten mountain communities with the highest number of recorded wildfire events within a 5-mile radius, based on CalFire’s historical perimeter dataset (1950–2024). To calculate these counts, each community’s 5-mile buffer was intersected with the statewide fire perimeter layer. Fires that overlapped the buffer were counted regardless of size, capturing the frequency of nearby fire activity.

Chart: Total Fires

Area Burned

This chart displays the ten mountain communities with the largest cumulative area burned within a 5-mile radius between 1950 and 2024. Burned area was calculated by intersecting the 5-mile buffer of each community with the historic wildfire perimeters, dissolving overlapping fires to avoid double-counting, and then summarizing the total acreage burned per buffer. Values were converted to square miles for consistent comparison.

Chart: Area Burned

Threat Classification Summary

This chart summarizes the number of mountain communities that fall within each of CalFire’s designated threat classifications. By categorizing communities based on their dominant fire threat rating. The chart provides a clear visual breakdown of fire risk distribution across the study area.

Chart: Threat Classification Summary

Conclusion

This data profile offers a spatial overview of wildfire activity and threat conditions across California’s mountain communities. By identifying communities based on elevation and slope, and analyzing their proximity to historic wildfire perimeters and current fire threat zones, the project provides useful context for understanding long-term fire exposure in these areas. While it does not predict future fire behavior or rank individual community risk, the statistics presented here can help inform awareness, planning, and resource allocation for both residents and decision-makers working to improve fire preparedness in California’s high-elevation regions.

Credits