How many climate zones does California have?

Sixteen building climate zones are defined in the California Energy Code.

How is my zone determined?

By the project location. Enter the ZIP code in the lookup on this page, which uses the California Energy Commission’s ZIP-code list; we confirm the zone from the full address when you order.

Do you prepare reports in every zone?

Yes, in all 16 California climate zones.

California Building Climate Zones

The California Energy Code divides the state into 16 building climate zones. Yours is set by project location, and it changes what the code requires.

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Climate zones group areas with similar heating and cooling demands so that requirements can be tuned to local conditions. They do not follow city or county lines, and a single ZIP code can span more than one — in which case the local jurisdiction may designate which applies.

Why the zone matters

Envelope and fenestration requirements vary by zone, and under the performance compliance approach the energy budget your design is measured against is itself zone-specific. The same building can comply in one zone and fail in another.

Find your zone

The answer comes from the California Energy Commission's ZIP-code list. Where a ZIP code spans more than one zone, the building department may designate which applies, so we confirm the zone from the project address when you order. The Commission also publishes an official climate zone tool.

All 16 zones

How the zones group

These groups are ours, not the Commission's, read from the weather location Joint Appendix JA2 gives each zone: coast and bay, zones 1 to 7; inland Southern California, 8 to 10; Central Valley, 11 to 13; desert, 14 and 15; mountain, 16.

Check your ZIP in the lookup above or the CEC's ZIP assignment list, or browse locations and counties.