Climate ZonesWashingtonLewis

Lewis, Washington HVAC Climate Zone

Lewis is located in IECC Climate Zone 4C (Mixed - Marine). Get accurate Manual J load calculations with official design temperatures for Lewis.

Climate Zone
4C
Winter Design
29°F
Summer Design
85°F
ZIP Codes
20

Lewis HVAC Contractors: Get Your Free Manual J Report

Climate Zone 4C requires precise load calculations. Upload your Lewis blueprint and get a professional Manual J report in 60 seconds— first report is FREE. Pre-loaded with Lewis's exact design temperatures (29°F winter / 85°F summer).

Claim Free Report
No credit card required

Verify Your Lewis ZIP Code

Enter your ZIP code to confirm it's in Lewis and get climate zone details.

Lewis covers 20 ZIP codes: 98336, 98355, 98356, 98361, 98377, 98531, 98532, 98533, 98538, 98539 and 10 more

Lewis Design Temperatures

Official ASHRAE design temperatures for Lewis, used for accurate Manual J load calculations.

Winter 99% Design Temp
29°F
Summer 1% Design Temp
85°F
Summer Wet Bulb
67°F

IECC Requirements for Zone 4C

Minimum insulation and window requirements for Lewis per IECC 2021.

Wall Insulation:R-20
Roof/Ceiling:R-49
Floor Insulation:R-19
Window U-Factor:0.32
Window SHGC:0.4

Energy Code: 2021 IECC

Recommended HVAC Equipment for Lewis

Heating Systems

Gas furnace
Heat pump
Typical AFUE
92-95%

Cooling Systems

AC (optional)
Heat pump
Typical SEER
14 SEER

Related Climate Zone Pages

Learn More About
Climate Zone 4C
View All Zones in
Washington
HVAC Permits for
Lewis, Washington

Get Free Manual J Calculations for Lewis

Upload your Lewis blueprint and get a professional Manual J load calculation using official Zone 4C design temperatures. First report is FREE.

Lewis design temps
Zone 4C compliant
Ready in 60 seconds
Upload Blueprint → Get Free Report

Join 10,000+ Lewis contractors who trust AutoHVAC