Downey, CA: Climate Zone, Risk and Window Requirements
Downey sits in IECC climate zone 3B, which sets the energy-performance bar for any window installed here. Below that, a short list of Downey'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
Downey's climate zone, in plain terms
Los Angeles County's normal precipitation runs about 13.3 inches a year, with 0.0 inches of snow, which is a separate question from energy performance but still shapes which window details matter in Downey.
Moisture and glass performance are handled by different parts of a window's spec sheet, and a Downey buyer benefits from checking both instead of assuming one implies the other.
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 6.7 mi away.
What FEMA's risk data says about Downey
FEMA scores Los Angeles County's winter-weather risk as Relatively Moderate and its flood risk as Very High.
Winter risk in Downey 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 Downey contractor, not one.
- 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 Downey 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.
Downey's longest-licensed window installers
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- Harris Glass COVerify license
- Compton Glass INCVerify license
- Galvez Glass ServiceVerify license
- E Z GlassVerify license
- Wgcustom Glazing LLCVerify license
- Rightway Glazing INCVerify license