Arlington, WA: Climate Zone, Risk and Window Requirements
Arlington sits in IECC climate zone 4C, which sets the energy-performance bar for any window installed here. Below that, a short list of Arlington's longest-licensed window contractors can turn a spec into an actual installed window.
Licenses checked · Washington State Department of Labor & Industries
4CIECC climate zone · ENERGY STAR Northern zone
Arlington's climate zone, in plain terms
Seattle-Tacoma-Bellevue, WA runs a January average near 38°F and climbs to about 63°F by July, a swing that adds up to roughly 5,834 heating degree days most winters, with 55 on the summer cooling side of the ledger.
That load is the actual argument for paying up for a better U-factor in Arlington, separate from anything a brochure claims.
Zone 4C's requirement is the floor; Arlington'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 2.2 mi away.
What FEMA's risk data says about Arlington
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 Arlington home.
Ask specifically about design pressure and impact rating for Arlington, not just energy performance, if either risk rating comes back on the high side.
- Strong wind
- Very Low
- Winter weather
- Relatively High
Data: FEMA, National Risk Index for Natural Hazards - County-level table, v1.20 (v1.20, December 2025).
Guides to finish before Arlington 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.
Arlington's longest-licensed window installers
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- General Storefronts INCVerify license
- Quantum Windows & DoorsVerify license
- Triple J Windows LLCVerify license
- Complete Siding And WindowsVerify license