Antioch, CA: Climate Zone, Risk and Window Requirements
Local risk and climate data for Antioch, CA are below, translated into plain terms for a window buyer rather than left as raw codes. Use it to check a proposed spec before you sign, not just to browse.
Licenses checked · California Contractors State License Board
3BIECC climate zone · ENERGY STAR South-Central zone
Antioch's climate zone, in plain terms
San Francisco-Oakland-Fremont, CA runs a January average near 48°F and climbs to about 76°F by July, a swing that adds up to roughly 2,230 heating degree days most winters, with 1,345 on the summer cooling side of the ledger.
That load is the actual argument for paying up for a better U-factor in Antioch, separate from anything a brochure claims.
Zone 3B's requirement is the floor; Antioch's specific load is what tells you whether beating that floor is worth the extra cost.
Data: U.S. EPA / DOE, ENERGY STAR, ENERGY STAR Version 7.0 Climate Zones by County/ZIP (Windows, Doors, and Skylights) (V7.0); Pacific Northwest National Laboratory (DOE Building America), Guide to Determining Climate Zone by County: Building America and IECC 2021 Updates (PNNL-33270) (2021 IECC), from the nearest NOAA station 2.5 mi away.
What FEMA's risk data says about Antioch
FEMA scores Contra Costa County's winter-weather risk as Very Low and its flood risk as Very High.
Winter risk in Antioch weighs on U-factor and condensation resistance; flood risk weighs more on sill height and drainage detailing than on the glass package.
Treat these as two separate conversations with a Antioch contractor, not one.
- Strong wind
- Relatively Low
- Winter weather
- Very Low
Data: FEMA, National Risk Index for Natural Hazards - County-level table, v1.20 (v1.20, December 2025).
Guides to finish before Antioch window bids come in
- How to Read an NFRC Window Label Four numbers on one sticker decide most of a window's real-world performance. Here's what each one means.
- ENERGY STAR Window Criteria by Climate Zone ENERGY STAR splits the country into four zones, each with its own numbers. Here they are, and why the Northern zone works backward from the other three.
- Impact Windows vs. Shutters in Florida's Hurricane Zones Florida gives homeowners two paths to a protected opening. Here's how each one is tested, and where the HVHZ raises the bar further.
Antioch's longest-licensed window installers
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- Glass TekVerify license
- Phoenix Glass & Consulting INCVerify license
- Viking Glass CompanyVerify license