California Climate Zone 10 is one of the 16 official climate zones the California Energy Commission uses to set Title 24 energy budgets. Title 24 is a statewide California energy code. Climate Zone 10 does not have its own separate rules — the same statewide standards apply, with the energy budget calibrated to this zone's climate. Your project's exact requirements are determined when your specific address is modeled in CEC-approved compliance software.
What Climate Zone 10 means
Each of California's 16 zones reflects distinct temperature, humidity, and solar conditions, and each has its own energy budget under Title 24. Climate Zone 10 is one of them.
Why Climate Zone 10 matters for Title 24
Although the standards are statewide, the budget your design must meet is calibrated to the zone — which can shift the emphasis between insulation, HVAC, windows, and solar. The exact targets are determined when your address is modeled.
The Climate in Zone 10 and What It Means for Your Report
Climate Zone 10 covers hot inland valleys of Southern California, including Riverside, San Bernardino and Ontario in the Inland Empire and inland San Diego County cities such as Escondido and El Cajon. Mountains and distance block most of the ocean's influence, so summers are hot and dry, with cooler nights and mild to cool winters.
Cooling usually dominates the energy model in Zone 10. Attic and roof design, window solar heat gain, west-facing glass, and duct location and sealing tend to decide whether a design complies, alongside the cooling efficiency of the heat pump or air conditioner. Heating still appears in winter, so the envelope has to work both ways, but measures that reduce summer heat gain generally have the biggest effect.
Cities & areas in Climate Zone 10
Climate zones are assigned by exact project address — often by ZIP code — and a single city can span more than one zone. The cities named on this page are examples only; we always confirm your zone from your project address. Browse our city Title 24 pages or read how cities map to Zone 10.
California Title 24 Climate Zone 10. Your project's zone is set by its address; see the California Energy Commission's official climate zone map for boundaries.
How Zone 10 affects HVAC
The zone's climate influences how heating and cooling are weighted in the model. Current Title 24 favors heat pumps statewide. Zone 10 HVAC requirements →
How Zone 10 affects windows
U-factor and SHGC targets are influenced by the zone's climate. Zone 10 window requirements →
How Zone 10 affects insulation
Wall, roof, and floor performance is measured against the zone's energy budget. Zone 10 insulation requirements →
How Zone 10 affects solar & heat pumps
Solar PV is required for most new low-rise residential statewide, with PV size set by your project; heat pumps are favored under current code. Solar & battery → · Heat pumps →
Common project types
Looking for a specific address? See every city and ZIP code in Climate Zone 10, taken from the California Energy Commission's official table, or use the climate zone ZIP code lookup.
Title 24 Guides for Climate Zone 10
The Climate Zone 10 Title 24 requirements page is the place to start. Because summer heat drives results here, the Zone 10 HVAC requirements, Zone 10 insulation requirements and Zone 10 window requirements are the next reads. The Zone 10 ADU guide and Zone 10 new home guide cover common projects in the region's growing suburbs, and Title 24 cost in Zone 10 covers pricing. For statewide background, see California Title 24 requirements and Title 24 calculations. City guides include Riverside and San Bernardino.
Climate zones follow the project address, not just the city name, and one city can straddle two zones. We confirm the exact zone from your address or ZIP code when we model the project; you can also check it yourself with our California climate zone lookup.
Title 24 pricing
- ADU — from $199
- Residential — from $245
- Multifamily — from $345
Standard turnaround: 2–3 business days. Rush (next business day): +$49 ADU / +$99 Residential / +$149 Multifamily. Super Rush (same day — typically completed within a few hours): +$150, subject to availability. Every report includes two revisions. See our pricing page.
What we need
- Architectural plans (PDF)
- Project address (this determines your climate zone)
- Scope of work
- Contact information
- Any plan-check comments (if available)
What we deliver
- Complete Title 24 energy report
- CF1R documentation (LMCC when applicable)
- CHEERS registration completed
- Professionally signed, permit-ready PDF package
- Two Revisions Included