Climate zones by state

Alabama Climate Zones by County

Alabama's 67 counties span climate zones 2A to 3A under the 2021 International Energy Conservation Code (IECC). Zone 3A is the most common, with 58 of the 67. For reference, Birmingham and Huntsville are in zone 3A and Mobile is in 2A.

Insulation minimums for each zone in Alabama

ZoneCountiesAtticWood-frame wallsFloors over unheated spaceBasement walls
2A9R-49R-13, or R-10ciR-13None required
3A58R-49R-20, or 13+5ci, or R-15ciR-19R-5ci or R-13

Minimums from the 2021 IECC (Table R402.1.3). Many areas still enforce an older edition, so check with your local building department. See sources.

Which energy code Alabama uses

Alabama enforces the 2015 IECC with amendments for homes (in effect since Oct 2016). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments. See every state's energy code.

What changed from the 2018 map

Seven counties moved one zone warmer in the 2021 map: Coffee County (3 → 2), Covington County (3 → 2), Dale County (3 → 2), Escambia County (3 → 2), Geneva County (3 → 2), Henry County (3 → 2), Houston County (3 → 2). If your town still enforces the 2018 or 2015 code, the older zone applies to permits.

Every county in Alabama

NameZone (2021)Zone (2018)Details
Autauga County3A3AInsulation →
Baldwin County2A2AInsulation →
Barbour County3A3AInsulation →
Bibb County3A3AInsulation →
Blount County3A3AInsulation →
Bullock County3A3AInsulation →
Butler County3A3AInsulation →
Calhoun County3A3AInsulation →
Chambers County3A3AInsulation →
Cherokee County3A3AInsulation →
Chilton County3A3AInsulation →
Choctaw County3A3AInsulation →
Clarke County3A3AInsulation →
Clay County3A3AInsulation →
Cleburne County3A3AInsulation →
Coffee County2A3A changedInsulation →
Colbert County3A3AInsulation →
Conecuh County3A3AInsulation →
Coosa County3A3AInsulation →
Covington County2A3A changedInsulation →
Crenshaw County3A3AInsulation →
Cullman County3A3AInsulation →
Dale County2A3A changedInsulation →
Dallas County3A3AInsulation →
DeKalb County3A3AInsulation →
Elmore County3A3AInsulation →
Escambia County2A3A changedInsulation →
Etowah County3A3AInsulation →
Fayette County3A3AInsulation →
Franklin County3A3AInsulation →
Geneva County2A3A changedInsulation →
Greene County3A3AInsulation →
Hale County3A3AInsulation →
Henry County2A3A changedInsulation →
Houston County2A3A changedInsulation →
Jackson County3A3AInsulation →
Jefferson County3A3AInsulation →
Lamar County3A3AInsulation →
Lauderdale County3A3AInsulation →
Lawrence County3A3AInsulation →
Lee County3A3AInsulation →
Limestone County3A3AInsulation →
Lowndes County3A3AInsulation →
Macon County3A3AInsulation →
Madison County3A3AInsulation →
Marengo County3A3AInsulation →
Marion County3A3AInsulation →
Marshall County3A3AInsulation →
Mobile County2A2AInsulation →
Monroe County3A3AInsulation →
Montgomery County3A3AInsulation →
Morgan County3A3AInsulation →
Perry County3A3AInsulation →
Pickens County3A3AInsulation →
Pike County3A3AInsulation →
Randolph County3A3AInsulation →
Russell County3A3AInsulation →
Shelby County3A3AInsulation →
St. Clair County3A3AInsulation →
Sumter County3A3AInsulation →
Talladega County3A3AInsulation →
Tallapoosa County3A3AInsulation →
Tuscaloosa County3A3AInsulation →
Walker County3A3AInsulation →
Washington County3A3AInsulation →
Wilcox County3A3AInsulation →
Winston County3A3AInsulation →

Source: Pacific Northwest National Laboratory, Guide to Determining Climate Zone by County: Building America and IECC 2021 Updates (2022).

Frequently asked questions

What climate zone is Alabama?

Alabama spans IECC climate zones 2A to 3A; zone 3A is the most common. Find your county in the table above, or search by ZIP code.

How much attic insulation do I need in Alabama?

The 2021 IECC calls for R-49 in the attic everywhere in Alabama.

What energy code does Alabama use?

Alabama enforces the 2015 IECC with amendments for homes (in effect since Oct 2016). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments.

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