Fire Hazard Severity Zones

Fire Hazard Severity Zones are areas in California that appear on fire zone maps and where physical conditions create moderate, high, and very high degrees of wildfire risk

A home with a wildfire in the background

What are Fire Hazard Severity Zones?

Fire Hazard Severity Zones are areas in California that are prone to wildfires. These areas were first mapped in 1992 by the California Department of Forestry and Fire Protection (CAL FIRE) to help officials, property owners, and builders better protect structures and infrastructure by identifying areas where the chance for wildfires is moderate to very high.

Originally, California’s fire zone map looked at state responsibility areas (SRAs) where the state is obligated to implement fire protection measures. Newer maps apply to SRAs and local responsibility areas (LRAs), or locations where local governments are responsible for fire protection. However, fire zone maps only show very high fire hazard zones for LRAs.

Urban areas are treated differently than wildlands on fire zone maps because they don’t have the same degree of risk for wildfire. However, those sitting on the fringe of the wildlands tend to be at higher risk than homes located within the cities and towns. Fire zone maps do account for potential home damage due to burning embers being moved by winds.

How are Fire Hazard Severity Zones determined?

CAL FIRE determines uses granular data to create its fire zone maps, looking specifically at factors that create fire hazards. These include each location’s:

  • Fire history. CAL FIRE considers an area’s history to determine the likelihood of wildfire over a 30- to 50-year period.
  • Vegetation This acts as fuel for a fire, so CAL FIRE looks at each area’s current vegetation and the potential changes over time.
  • Weather. Hot, dry, and windy climates cause fires to spread faster.
  • Topography. Fire often burns faster moving up steep slopes.
  • Crown fire potential. Fires that burn through the top layer of foliage are usually the most intense and most difficult to contain.
  • Ember production and movement. Burning embers blown ahead of a wildfire are a major cause of fire spread, especially of fire spread to urban areas.

Essentially, officials are looking at the likelihood of a wildfire erupting and spreading based on whether or not a fire has occurred in the same or nearby area and how much vegetation there is to fuel the fire. They then consider prior fire patterns in areas with similar geographic qualities such as mountain slopes and wind patterns.

What is the fire zone map used for?

Understanding the wildfire risks in their area helps homeowners defend against the risk. For example, every home located within a moderate, high, or very high-risk zone should have at least 100 feet of defensible space as a buffer between vegetation and your property. This is most often accomplished by clearing away brush.

New homebuyers should be aware of fire zone maps and check if the property they’re interested in is in an FHSZ, too, because it can make buying homeowners insurance complicated. This information should be disclosed before the sale is completed.

Builders can also use fire zone maps to make sure they meet building standards for new construction and the infrastructure around new structures. This includes using fire-resistant roofing materials and closing off home eaves on a home’s perimeter.

Finally, state and local officials need to know the FHSZ in their areas so they can make smart choices when allocating resources each year. For instance, they may need to increase road widths to make it easier for fire and rescue units to move quickly.

How to tell if your home is in a Fire Hazard Severity Zone

You can use the California Fire Hazard Severity Zone Viewer to view California’s fire zone map. To see your specific property, click on the binocular icon on the left side of the map and enter your address. Remember, however, that this map only shows SRAs with a moderate to very high fire hazard exposure and LRAs with very high exposure, as indicated by the legend to the right of the map. If your property is in an LRA with moderate or high exposure, this map won’t show it.

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