HomeMy WebLinkAboutStaff Report 2507-4976CITY OF PALO ALTO
CITY COUNCIL
Special Meeting
Monday, August 11, 2025
Council Chambers & Hybrid
5:30 PM
Agenda Item
4.Ordinance Adopting the 2025 Fire Hazard Severity Zone Map Issued by the State Fire
Marshal
City Council
Staff Report
From: City Manager
Report Type: CONSENT CALENDAR
Lead Department: Fire
Meeting Date: August 11, 2025
Report #:2507-4976
TITLE
Ordinance Adopting the 2025 Fire Hazard Severity Zone Map Issued by the State Fire Marshal
RECOMMENDATION
Staff recommends that the City Council adopt the CAL FIRE Hazard Severity Zone (FHSZ) map, as
recommended by the California Department of Forestry and Fire Protection (CAL FIRE), for
areas within the City of Palo Alto’s jurisdiction (local responsibility area).
EXECUTIVE SUMMARY
CAL FIRE is mandated by state law to identify and map areas with significant fire hazards and
periodically revise and update its designation of zones. These maps, known as Fire Hazard
Severity Zone (FHSZ) maps, categorize areas based on factors that influence fire likelihood and
behavior. Updates in state law since 2021 now require that a local agency, including the City of
Palo Alto, designate by ordinance the moderate, high, and very high FHSZs in its jurisdiction after
receiving recommendations from the State Fire Marshal. (Gov. Code 51179(a)).
Recent updates to the state’s FHSZ maps were issued for the Bay Area, including Palo Alto,
February 24, 2025.The City provided opportunities for public review and comment on the CAL
FIRE FHSZ map from March 26 through April 30, 2025, and adoption of the CAL FIRE FHSZ map is
a necessary next step to protect the City of Palo Alto from the increasing threat of wildfires. It
ensures compliance with state law, enhances public safety, and promotes responsible land-use
planning. Staff recommends that the City Council adopt the map as presented. Under state law,
a local agency has discretion to add areas not identified by the State Fire Marshal or increase the
fire hazard severity identified by the state, but not to remove areas or reduce the hazard severity
level (Gov. Code 51179(b)). Staff recommends adopting the local FHSZ maps as issued by CAL
FIRE, without revisions.
This is part of multiple items regarding wildfire preparedness and in support of the City Council
priorities for 2025. The details within this staff report, an audit on wildfire preparedness and
community conversations with those neighborhoods in the WUI held in June 2025.
BACKGROUND
The State Fire Marshal is required to classify lands within State Responsibility Areas (SRA) into
fire hazard severity zones. In 1992, Assembly Bill 337 required CAL FIRE to evaluate fire hazard
severity in local responsibility areas and make a recommendation to the local jurisdictions
where Very High FHSZ exists. Under Senate Bill 63 (Stern, 2021) Government Code 51178 was
amended to also identify the Moderate and High Fire Hazard Severity Zones with the Very High
in Local Responsibility Areas (LRA). Each zone must encompass relatively homogeneous lands
and be based on fuel loading, slope, fire weather, and other relevant factors, including areas
where winds have been identified as a major cause of wildfire spread.
The FHSZ maps are essential tools for the following:
Wildfire Preparedness: They provide critical information for residents, property
owners, and the City to understand the level of fire hazard in specific areas.
Building Codes: The maps inform building code requirements, particularly for
new construction and renovations, to enhance structural resistance to wildfire.
Defensible Space: The maps guide the implementation and enforcement of
defensible space regulations, which are crucial for protecting structures from
approaching wildfires.
Emergency Planning: The maps assist in developing effective wildfire mitigation
and response plans.
Designating areas where California’s defensible space standards and wildland
urban interface building codes are required.
General plan considerations: Local governments may consider them in their
general plans.
Recent changes in state law, specifically Government Code Section 51179, require local
agencies to adopt these maps by ordinance. The City of Palo Alto has received the updated
FHSZ map from CAL FIRE, which designates areas within our jurisdiction as Moderate, High, or
Very High Fire Hazard Severity Zones.
ANALYSIS
According to CAL FIRE, the maps are developed using a science-based and field-tested model
that assigns a hazard score based on the factors that influence fire likelihood and fire behavior.
CAL FIRE is updating these maps to more accurately reflect the zones in California that are
susceptible to wildfire, incorporating new science in local climate data and improved fire
assessment modeling. The maps evaluate “hazard,” not “risk”. They are like flood zone maps,
where lands are described in terms of the probability level of a particular area being inundated
by floodwaters, and not specifically prescriptive of impacts. Adopting this map is crucial for
several reasons:
Compliance with State Law: State law mandates that local agencies
adopt the FHSZ maps.
Enhanced Public Safety: Adopting the map enables the City to better
protect its residents and property from the increasing threat of wildfires. It
provides a foundation for implementing effective mitigation measures and
enforcing necessary regulations.
Improved Planning and Development: The map will inform land-use
planning and development decisions, ensuring that new construction and
infrastructure projects are designed to minimize fire risks.
Access to Funding: Adoption of the FHSZ maps may be a prerequisite
for accessing certain state and federal funding for wildfire prevention
and mitigation projects.
Understanding Fire Hazard Severity Zones: It is important to note that the
Fire Hazard Severity Zone map evaluates "hazard," not "risk." "Hazard" is
based on the physical conditions that create a likelihood and expected fire
behavior over a 30 to 50-year period without considering mitigation
measures. "Risk" is the potential damage a fire can do to the area under
existing conditions, accounting for modifications such as fuel reduction
projects, defensible space, and ignition-resistant construction.
City staff has reviewed the CAL FIRE FHSZ map and recommends its adoption as issued. A
description of how the maps are developed is provided here: Fire Hazard Severity Zones |
OSFM1. Below summarizes elements of the FHSZ maps and how they were developed.
Key elements of the Fire Hazard Severity Zone model: The fire hazard severity model for
wildland fire has two key elements: 1) probability of an area burning and 2) expected fire
behavior under extreme fuel and weather conditions. The zones reflect areas that have similar
burn probabilities and fire behavior characteristics.
Factors considered in determining fire hazard within wildland areas are
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.
FHSZs are not a structure loss model, as key information regarding
structure ignition (such as roof type, etc.) is not included.
1 Fire Hazard Severity Zones | OSFM https://osfm.fire.ca.gov/what-we-do/community-wildfire-preparedness-and-
mitigation/fire-hazard-severity-zones
The model places an emphasis on the spread of embers. Embers can
travel long distances in the wind and ignite vegetation, roofs, attics,
and decks.
Areas immediately adjacent to wildland receive the same FHSZ score as
that wildland where fire originates, and the model then produces lower
scores as the distance to the wildland edge increases.
In wildland areas, zone edges are a result of the way zones are
delineated. Zones represent areas of similar slope and fuel potential.
How Fire Hazard Severity Zones are determined: CAL FIRE used the best available science and
data to develop and field-test a model that served as the basis of zone assignments. The model
evaluated the probability of the area burning and potential fire behavior in the area.
Many factors were included, such as fire history, vegetation, flame
length, blowing embers, proximity to wildland, terrain, and weather.
A 2 km grid of climate data covering the years 2003-2018 is being used in the
models underlying the 2025 map update. The previous model used stock
weather inputs across the state to calculate wildland fire intensity scores.
The updated model adjusts fire intensity scores based on the most extreme
fire weather at a given location, considering temperature, humidity, and
wind speed.
Ember transport is being modeled based on local distributions of observed
wind speed and direction values instead of using a generic buffer distance
for urban areas adjacent to wildlands.
Classification of a wildland zone as Moderate, High, or Very High fire hazard
is based on the average hazard across the area included in the zone, which
have a minimum size of 200 acres.
In wildlands, hazard is a function of modeled flame length under the worst
conditions and annual burn probability. Classification outside of wildland
areas is based on the fire hazard of the adjacent wildland and the probability
of flames and embers threatening buildings.
State Responsibility Area (SRA): SRA is the area where the state has financial
responsibility for wildland fire protection and prevention. Incorporated cities and
federal ownership are not included in SRA. CAL FIRE is responsible for fire
prevention and suppression within the SRA.
Local Responsibility Area (LRA): Local Responsibility Areas (LRA) are incorporated
cities, urban regions, agricultural lands, and portions of the desert where the local
government is responsible for wildfire protection. CAL FIRE uses an extension of the
state responsibility area Fire Hazard Severity Zone model as the basis for evaluating
fire hazard in Local Responsibility Area.
The Local Responsibility Area hazard rating reflects flame and ember
intrusion from adjacent wildlands and from flammable vegetation in the
urban area.
CAL FIRE’s Land Use Planning Program provides support to local
governments by providing fire safety expertise on the State’s wildland
urban interface building codes, wildfire safety codes, as well as helping in
the development of the safety elements in general plans.
CAL FIRE uses the same modeling data that is used to map the State
Responsibility Area for Local Responsibility Areas.
New legislation, Senate Bill 63 (Stern, 2021), now requires the adoption of all
three Fire Hazard Severity Zone classes in the Local Responsibility Area.
Previously only Very High Fire Hazard Severity Zones were required for
adoption in Local Responsibility Areas.
FISCAL/RESOURCE IMPACT
Adoption of the Ordinance to adopt the FHSZ map does not have direct fiscal
impacts. Chapter 7A of the California Building Code and Chapter 49 of the California
Fire Code are already being enforced in all areas identified as ”Moderate”, ”High”, or
”Very High” fire hazard severity zones on the updated maps.
However, additional resources, including staff time and funding for public education,
mitigation efforts and outreach may be required. Though these costs can most likely
be absorbed within existing budgets, future budget requests may be necessary.
STAKEHOLDER ENGAGEMENT
The City is committed to comprehensive stakeholder engagement throughout the
process to adopt and implement updates to the CAL FIRE Fire Hazard Severity Zone
(FHSZ) maps. To facilitate public awareness and access to relevant information, the
City published details on its official website, and the Uplift Local newsletter,
including direct links to supplementary resources. The FHSZ information was made
available for a 35-day public comment period.
ENVIRONMENTAL REVIEW
Adoption of the Ordinance to adopt the 2025 FHSZ map does not have a direct
environmental impact and is not a project under the California Environmental
Quality Act. However, the map will help guide mitigation efforts outlined in the
updated Foothills Fire Management Plan (FFMP), which is subject to a CEQA
exemption.
ATTACHMENTS
Attachment A: Ordinance of the Council of the City of Palo Alto adopting the 2025 Fire Hazard
Severity Zone Map Issued by the State Fire Marshal
APPROVED BY:
Geoffrey Blackshire, Fire Chief
NOT YET APPROVED Attachment A
1
027072325
Ordinance No. ____
Ordinance of the Council of the City of Palo Alto adopting the 2025 Fire Hazard Severity Zone
Map Issued by the State Fire Marshal
The Council of the City of Palo Alto does ORDAIN as follows:
SECTION 1. Findings and Declarations. The City Council finds and declares as follows:
A. To better prepare for wildfires, the California Department of Forestry and Fire Protection
(CAL FIRE) is required to periodically review its recommended classifications of fire hazard
severity zones throughout California. The state legislature has found that the prevention
of wildfires is a matter of statewide concern, not a municipal affair.
B. The State released updated 2025 Fire Hazard Severity Zone (FHSZ) maps, and requires all
local jurisdictions, including Palo Alto, with moderate, high, and very high fire hazard
severity zone recommendations to designate those zones by ordinance.
C. State law also requires that the City post the maps indicating CAL FIRE’s FHSZ
recommendations publicly for comment within 30 days of receipt, which the City
conducted from March 26 - April 30, 2025.
D. After consideration of public comments, the City will rely on the latest recommendations
of CAL FIRE in its published FHSZ maps, notwithstanding local discretion to impose more
restrictive fire and public safety requirements.
SECTION 2. Adoption of 2025 Fire Hazard Severity Zone Map for Palo Alto.
The City hereby designates the Fire Hazard Severity Zones as recommended by the California
Department of Forestry and Fire Protection pursuant to Government Code Section 51178. The
map, approved by the Council of the City of Palo Alto, is hereby incorporated by reference, and
entitled, “Fire Hazard Severity Zones in Local Responsibility Area - City of Palo Alto”, dated
February 24, 2025 (Exhibit A).
The official map is also located electronically on the following website:
https://www.paloalto.gov/wildfire
SECTION 3. Effective Date. This Ordinance shall be effective on the thirty-first date
after the date of its adoption.
//
//
//
NOT YET APPROVED Attachment A
2
027072325
SECTION 4. CEQA. The City Council finds and determines that this Ordinance is not a
project within the meaning of section 15378 of the California Environmental Quality Act
(“CEQA”) Guidelines because adoption of the state FHSZ map and updating a statutory
definition involves no action with potential for resulting in physical change in the environment,
either directly or ultimately. In the event that this Ordinance is found to be a project under
CEQA, it is subject to the CEQA exemption contained in CEQA Guidelines section 15061(b)(3)
because it can be seen with certainty to have no possibility of a significant effect on the
environment in that this Ordinance simply clarifies existing local regulations.
INTRODUCED AND PASSED:
AYES:
NOES:
ABSENT:
ABSTENTIONS:
ATTEST:
__________________________ _____________________________
City Clerk Mayor
APPROVED AS TO FORM: APPROVED:
__________________________ _____________________________
City Attorney or designee City Manager
_____________________________
Fire Chief, Palo Alto Fire Department
City and County boundaries as of 10/22/24 (CA Board of Equalization)
CAL FIRE State Responsibility Areas (SRA25_1)
CAL FIRE Fire Hazard Severity Zones (FHSZSRA23_3, FHSZLRA_25_1)
Data Sources:
Daniel Berlant, State Fire Marshal, CA Department of Forestry and Fire Protection
Joe Tyler, Director/Fire Chief, CA Department of Forestry and Fire Protection
Wade Crowfoot, Secretary for Natural Resources, CA Natural Resources Agency
Gavin Newsom, Governor, State of CaliforniaThe State of California and the Department of Forestry and FireProtection make no representations or warranties regarding theaccuracy of data or maps. Neither the State nor the Department shallbe liable under any circumstances for any direct, special, incidental,or consequential damages with respect to any claim by any user orthird party on account of, or arising from, the use of data or maps.
and other relevant factors including areas where windshave been identified by the Office of the State Fire Marshalas a major cause of wildfire spread.
statewide criteria and based on the severity of fire hazard that isexpected to prevail in those areas. Moderate, high, and very high firehazard severity zones shall be based on fuel loading, slope, fire weather,
Government Code section 51178 requires the State FireMarshal to identify areas in the state as moderate, high,and very high fire hazard severity zones based on consistent
Waterbody
Federal ResponsibilityArea (FRA)Unzoned LRA
Incorporated City
Projection: NAD 83 California Teale AlbersScale: 1:97,000 at 11" x 17"
0 1 2 3 4 5 6 7Km
0 1 2 3 4Mi
Very High High Moderate
Fire Hazard Severity Zones in State Responsibility Area(SRA), Effective April 1, 2024
Very High High Moderate
Fire Hazard Severity Zones (FHSZ) in Local ResponsibilityArea (LRA), as Identified by the State Fire Marshal
Palo Alto
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February 24, 2025
As Identified by theState Fire MarshalLocal Responsibility Area
Fire Hazard Severity Zones
CITY OF PALO ALTO – SANTA CLARA COUNTY
Exhibit A