Glendora, CA: Climate Zone, Risk and Window Requirements
Glendora sits in IECC climate zone 3B, which sets the energy-performance bar for any window installed here. Below that, a short list of Glendora's longest-licensed window contractors can turn a spec into an actual installed window.
Licenses checked · California Contractors State License Board
3BIECC climate zone · ENERGY STAR South-Central zone
Glendora's climate zone, in plain terms
Glendora falls in IECC climate zone 3B, and ENERGY STAR separately groups Los Angeles County into its South-Central zone for window certification.
Those two numbers, not the brand on the box, set the U-factor and SHGC worth checking on any quote you get in Glendora.
A Los Angeles-Long Beach-Anaheim, CA contractor who can't name either one on request is worth a second question before you sign.
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 0.2 mi away.
What FEMA's risk data says about Glendora
Neither rating changes a window's energy label, but both are exactly what impact-resistance and design-pressure ratings are built to answer for a Glendora home.
Ask specifically about design pressure and impact rating for Glendora, not just energy performance, if either risk rating comes back on the high side.
- Strong wind
- Relatively Moderate
- Winter weather
- Relatively Moderate
Data: FEMA, National Risk Index for Natural Hazards - County-level table, v1.20 (v1.20, December 2025).
Guides to finish before Glendora 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.
Glendora's longest-licensed window installers
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- Corona Aluminum COVerify license
- Glendora Glass And Mirror LLCVerify license
- All Cities Glass And ScreenVerify license
- Mariba Construction INCVerify license