01Key facts / TL;DR
Yes, California uses 16 building climate zones for Energy Code weather data and climate-specific provisions; they are not city, county or plant-hardiness boundaries.
No, a listed ZIP assignment or reference weather city is not proof of your parcel’s climate zone. A ZIP can cross climate regions; ask whether your AHJ elects to use the CEC postal assignment.
Yes, use the reference lookup below as a starting point, then confirm the exact project location with the official CEC map and record the applicable application date.
Climate zone lookup
Find the listed California climate zone
Search CEC listed ZIP assignments or the 16 reference weather locations. Works without JavaScript: the form submits and the page returns your result.
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Start with a ZIP or reference city
This is a curated CEC reference, not a complete city directory or parcel lookup.
Enter a California ZIP code or one of the reference city names below, then submit. The result appears here after the page reloads.
How this lookup works
- A five-digit ZIP is matched to the CEC ZIP workbook, a postal convenience list. ZIPs can cross zone boundaries, so all listed zones are shown.
- A partial ZIP shows every possible listed zone. It never picks one.
- A city name matches only the 16 CEC reference weather locations (JA2 Table 2-1). That is the weather file location, not a zone for the whole city.
- Confirm the exact project location on the CEC map before relying on any result.
What a climate zone means
A climate zone selects the weather data used in compliance calculations and which climate-specific energy provisions apply. It is not a universal heating or cooling prescription, and the numbering is not a simple hot-to-cold ranking.
The 16 reference weather locations
- ArcataZone 1
- Santa RosaZone 2
- OaklandZone 3
- San Jose-ReidZone 4
- Santa MariaZone 5
- TorranceZone 6
- San Diego-LindberghZone 7
- FullertonZone 8
- Burbank-GlendaleZone 9
- RiversideZone 10
- Red BluffZone 11
- SacramentoZone 12
- FresnoZone 13
- PalmdaleZone 14
- Palm Springs-IntlZone 15
- Blue CanyonZone 16
Source: California Energy Commission, Climate Zone Tool, Maps, and Information, and the CEC climate zone map.
Coverage: 168 curated five-digit ZIP entries, three-digit prefix summaries and 16 reference weather locations. Verified against the CEC ZIP workbook and 2025 Joint Appendix JA2, Table 2-1 on November 6, 2026. The ZIP workbook currently linked by CEC has a 2020 file path; it is not represented here as a new 2025 parcel map.
Educational lookup, not a parcel determination or compliance decision. ZIP codes can cross climate zone boundaries. Confirm the exact project location with the CEC map, and confirm requirements with your building department (AHJ); the AHJ and your permit application date still govern.
02Sixteen zones for building energy purposes
The Energy Code divides California into 16 building climate zones. They are defined for energy compliance and are distinct from other climate classifications such as plant hardiness zones or general weather descriptions. Each zone has associated weather data used in compliance software and, in many cases, different prescriptive requirements.
03Zone boundaries do not follow county lines
A single county can contain more than one climate zone, and neighboring addresses can occasionally fall in different zones. Assuming a zone from a nearby town, a county name or an earlier project is a common source of error. Using the wrong zone can mean using the wrong requirements, which may invalidate documentation and cause plan check corrections.
04How to confirm your zone
A reliable process looks like this:
- +Use the CEC climate zone tool and maps with the exact project address or parcel information
- +If the result is near a boundary or unclear, ask the reviewing building department
- +Record the confirmed zone on the drawings and share it with the documentation preparer
- +Keep a copy of the lookup with the project file
05What the zone influences
Climate zone can affect required insulation levels, window performance values, equipment requirements and the weather data used in performance modeling. It can also shape which design choices have the biggest effect, which is why confirming it before design decisions is useful rather than a formality.
This page explains general concepts only. The CEC is the authoritative source for zone definitions and lookup tools.
06Common pitfalls
Several pitfalls recur. Copying a zone from a previous project in the same county is one. Using a mailing address that differs from the parcel location is another, especially for rural properties with post office boxes. Assuming a zone from a nearby city name can also mislead. For projects with multiple parcels or phases, confirm each one. When the preparer receives drawings, the confirmed zone should be stated clearly so that it is visible to everyone, including the plan reviewer, who will compare it with their own lookup.
Remember, too, that the zone is only one input. Orientation, building shape, glazing and equipment all interact with it, so two homes in the same zone can still need quite different measures.