Window Climate Specs for Fremont, CA
Fremont sits in IECC climate zone 3C, which sets the energy-performance bar for any window installed here. Below that, a short list of Fremont's longest-licensed window contractors can turn a spec into an actual installed window.
Licenses checked · California Contractors State License Board
3CIECC climate zone · ENERGY STAR South-Central zone
What zone 3C means for a Fremont window
San Francisco-Oakland-Fremont, CA runs a January average near 50°F and climbs to about 67°F by July, a swing that adds up to roughly 2,288 heating degree days most winters, with 430 on the summer cooling side of the ledger.
That load is the actual argument for paying up for a better U-factor in Fremont, separate from anything a brochure claims.
Zone 3C's requirement is the floor; Fremont'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 5.2 mi away.
Storm and weather risk around Fremont
FEMA scores Alameda County's winter-weather risk as Very Low and its flood risk as Very High.
Winter risk in Fremont 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 Fremont contractor, not one.
- Strong wind
- Very 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 Fremont 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.
Window installers with the longest license records in Fremont
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- Quality Glass INCVerify license
- Walters & WolfVerify license
- Cline Glass Contractors INCVerify license
- Bay Valley Insulation INCVerify license
- Econo Glass INCVerify license
- Salinas GlassVerify license
- Creative Shower Door CorpVerify license
- Alliance Glass CompanyVerify license
- Classic Glass & Shower INCVerify license
- Golden State Shower Door INCVerify license
- R & R Insulated Glass ProductsVerify license
- Prime Builders Develop INCVerify license