Fire Hazard Severity Zones

ilThe Fire Hazard Severity Zone map, provided by the California Office of the State Fire Marshal, designates over 90% of the City’s geography as a Fire Hazard Severity Zone. The designation carries legal requirements for fire safety and reinforces the fact that our community is subject to the threat of wildfire. Recognition of this hazard allows us to take steps to reduce our risk and lessen the impact of wildfire when it occurs. 

The state has identified three levels of fire hazard severity: Very High, High, and Moderate. The City has identified additional Wildland Urban Interface Areas based on similar criteria. Review the Frequently Asked Questions to learn more about Fire Hazard Severity Zones and search your address using the interactive map.

Frequently Asked Questions

History of Fire Hazard Severity Zones in the City of Poway

The City of Poway first designated hazardous fire areas in November 2007, after experiencing the devastation of the 2003 Cedar Fire and the 2007 Witch Fire. Hazardous fire areas were considered to be at greater risk for wildfire due to their proximity to highly flammable vegetation including the native chapparal that is present in much of Poway’s open space areas. The map was used to implement the International Wildland Urban Interface Building Code which provided a comprehensive approach to building construction methods and materials and vegetative fuel management practices to reduce the risk of fire spreading from the wildland to a structure.

In 2009, the State of California issued a fire hazard map that identified Very High Fire Hazard Severity Zone areas within the City. The state map was a cooperative effort between the California Department of Forestry and Fire Protection (CAL FIRE) and the University of California. It utilized a comprehensive and detailed methodology to evaluate potential fire behavior, fuel, terrain, and weather. The state map included some areas of the City not previously identified as a hazardous fire area and excluded other areas considered by the City to be a hazardous fire area.

The two maps were combined to create the City of Poway Very High Fire Hazard Area map, which has been in use ever since.

What is a Fire Hazard Severity Zone?

The State of California has declared that wildfire poses a serious threat to the preservation of the public peace, health, and safety and are a matter of statewide concern.

The Fire Hazard Severity Zone measures the hazard that is present, not the risk. Hazard is based on physical conditions that create a likelihood of fire occurrence and expected fire behavior without considering mitigation measures such as home hardening or fuel reduction efforts. Risk is the potential damage a fire can do to the area under existing conditions, accounting for any modifications such as fuel reduction projects, defensible space, and ignition resistant building construction.

The greater the hazard, the greater the measures that should be taken to reduce the risk. The classifications assist the City in identifying proper fire mitigation measures to minimize the loss of life, property, and resources in those areas. Both the state and the City have adopted requirements for risk reduction measures in fire hazard severity zones.

Who is responsible for Fire Hazard Severity Zones?

The California Department of Forestry and Fire Protection (CAL FIRE) has been directed by the state Legislature to identify moderate, high, or very high fire hazard severity zones throughout the state. CAL FIRE uses a scientific model to predict the probability of an area burning and expected fire behavior including predicted ember spread. The state is expected to review Fire Hazard Severity Zones every five years.  

Visit CALFIRE’s Fire Hazard Severity Zones website to learn more.

The City of Poway may be more restrictive than the state in identifying fire hazards but cannot be less restrictive. The City will not make changes to the map produced by CAL FIRE but may identify any geographic area as a Hazardous Fire Area because the type and condition of vegetation, topography, weather and structure density increase the probability that the area will be susceptible to wildfire.

What are the key elements of the Fire Hazard Severity Zone Model?

The model has two key elements: probability of an area burning and expected fire behavior under extreme fuel and weather conditions. The factors considered in determining fire hazard within wildland areas is fire history, flame length, terrain, local weather, and potential fuel over a 50-year period. Outside of wildlands, the model considers factors that might lead to buildings being threatened, including terrain, weather, urban vegetation cover, blowing embers, proximity to wildland, fire history, and fire hazard in nearby wildlands. This is not a structure loss model, as key information regarding structure ignition is not included.

Classification of an area as Moderate, High, or Very High fire hazard severity is based on the average hazard across the area included in the zone. In wildlands, hazard is a function of modeled flame length under the worst conditions and annual burn probability. Both these factors generally increase with an increasing hazard level, but there may be instances where one value is Very High and the other is low, pushing the overall hazard into a more intermediate ranking. On average, both modeled flame length and burn probability increase by roughly 40-60% between hazard classes. Classification outside of wildland areas is based on the fire hazard of the adjacent wildland and the probability of flames and embers threatening buildings.  

What does this mean for my insurance?

The Fire Hazard Severity Zones are intended to drive local planning decisions, not insurance decisions. Insurance companies use risk models, which differ from hazard models, because they consider the susceptibility of a structure to damage from fire and other short-term factors that are not included in hazard modeling. Insurance risk models incorporate additional factors that change more frequently than those that are included in the hazard modeling, which is built to remain steady.

Reducing wildfire risks throughout the state is the primary way that insurance can become more available and more affordable. The Fire Hazard Severity Zone map supports that goal through improving public education about the hazard and the need for safety preparation.

Learn how to reduce your risk to wildfire.

What are the requirements for property owners with a Fire Hazard Severity Zone?

Property owners in the Very High Fire Hazard Severity Zone are subject to the following regulations:

Property owners in the High Fire Hazard Severity Zone are subject to the following regulations:

There are currently no regulations for property owners in the Moderate Fire Hazard Severity Zone but all Poway residents are encouraged to be prepared for wildfire.

What if my property is partially in one or more Fire Hazard Severity Zones?

The City of Poway will implement a policy that when a parcel is within one or more fire hazard severity zones or is partially included in a fire hazard severity zone, the entirety of the parcel shall fall under the most restrictive of the fire hazard zones identified. This policy will ensure that the greatest level of mitigation measures is applied to the parcel to reduce the risk of wildfire impacting your home.

My home is in the City of Poway Wildfire Defensible Space Program. How do the Fire Hazard Severity Zones affect me?

The Wildfire Defensible Space Program requires the management of highly flammable chapparal within the 100-foot defensible space surrounding a structure regardless of the Fire Hazard Severity Zone. The City of Poway Fire Department is currently reviewing the Wildfire Defensible Space Program to determine how this program can be incorporated into the broader defensible space requirements.