Climate zones by state

Missouri Climate Zones by County

Missouri's 115 counties span climate zones 3A to 5A under the 2021 International Energy Conservation Code (IECC). Zone 4A is the most common, with 87 of the 115. For reference, St. Louis, Kansas City and Springfield are in zone 4A.

Insulation minimums for each zone in Missouri

ZoneCountiesAtticWood-frame wallsFloors over unheated spaceBasement walls
3A2R-49R-20, or 13+5ci, or R-15ciR-19R-5ci or R-13
4A87R-60R-30, or 20+5ci, or 13+10ci, or R-20ciR-19R-10ci or R-13
5A26R-60R-30, or 20+5ci, or 13+10ci, or R-20ciR-30R-15ci, or R-19, or 13+5ci

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 Missouri uses

Missouri has no statewide residential energy code; cities and counties adopt their own, so check with your local building department. 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

Six counties moved one zone warmer in the 2021 map: Buchanan County (5 → 4), Caldwell County (5 → 4), Chariton County (5 → 4), Clinton County (5 → 4), Dunklin County (4 → 3), Pemiscot County (4 → 3). If your town still enforces the 2018 or 2015 code, the older zone applies to permits.

Every county in Missouri

NameZone (2021)Zone (2018)Details
Adair County5A5AInsulation →
Andrew County5A5AInsulation →
Atchison County5A5AInsulation →
Audrain County4A4AInsulation →
Barry County4A4AInsulation →
Barton County4A4AInsulation →
Bates County4A4AInsulation →
Benton County4A4AInsulation →
Bollinger County4A4AInsulation →
Boone County4A4AInsulation →
Buchanan County4A5A changedInsulation →
Butler County4A4AInsulation →
Caldwell County4A5A changedInsulation →
Callaway County4A4AInsulation →
Camden County4A4AInsulation →
Cape Girardeau County4A4AInsulation →
Carroll County4A4AInsulation →
Carter County4A4AInsulation →
Cass County4A4AInsulation →
Cedar County4A4AInsulation →
Chariton County4A5A changedInsulation →
Christian County4A4AInsulation →
Clark County5A5AInsulation →
Clay County4A4AInsulation →
Clinton County4A5A changedInsulation →
Cole County4A4AInsulation →
Cooper County4A4AInsulation →
Crawford County4A4AInsulation →
Dade County4A4AInsulation →
Dallas County4A4AInsulation →
Daviess County5A5AInsulation →
DeKalb County5A5AInsulation →
Dent County4A4AInsulation →
Douglas County4A4AInsulation →
Dunklin County3A4A changedInsulation →
Franklin County4A4AInsulation →
Gasconade County4A4AInsulation →
Gentry County5A5AInsulation →
Greene County4A4AInsulation →
Grundy County5A5AInsulation →
Harrison County5A5AInsulation →
Henry County4A4AInsulation →
Hickory County4A4AInsulation →
Holt County5A5AInsulation →
Howard County4A4AInsulation →
Howell County4A4AInsulation →
Iron County4A4AInsulation →
Jackson County4A4AInsulation →
Jasper County4A4AInsulation →
Jefferson County4A4AInsulation →
Johnson County4A4AInsulation →
Knox County5A5AInsulation →
Laclede County4A4AInsulation →
Lafayette County4A4AInsulation →
Lawrence County4A4AInsulation →
Lewis County5A5AInsulation →
Lincoln County4A4AInsulation →
Linn County5A5AInsulation →
Livingston County5A5AInsulation →
Macon County5A5AInsulation →
Madison County4A4AInsulation →
Maries County4A4AInsulation →
Marion County5A5AInsulation →
McDonald County4A4AInsulation →
Mercer County5A5AInsulation →
Miller County4A4AInsulation →
Mississippi County4A4AInsulation →
Moniteau County4A4AInsulation →
Monroe County4A4AInsulation →
Montgomery County4A4AInsulation →
Morgan County4A4AInsulation →
New Madrid County4A4AInsulation →
Newton County4A4AInsulation →
Nodaway County5A5AInsulation →
Oregon County4A4AInsulation →
Osage County4A4AInsulation →
Ozark County4A4AInsulation →
Pemiscot County3A4A changedInsulation →
Perry County4A4AInsulation →
Pettis County4A4AInsulation →
Phelps County4A4AInsulation →
Pike County5A5AInsulation →
Platte County4A4AInsulation →
Polk County4A4AInsulation →
Pulaski County4A4AInsulation →
Putnam County5A5AInsulation →
Ralls County5A5AInsulation →
Randolph County4A4AInsulation →
Ray County4A4AInsulation →
Reynolds County4A4AInsulation →
Ripley County4A4AInsulation →
Saline County4A4AInsulation →
Schuyler County5A5AInsulation →
Scotland County5A5AInsulation →
Scott County4A4AInsulation →
Shannon County4A4AInsulation →
Shelby County5A5AInsulation →
St. Charles County4A4AInsulation →
St. Clair County4A4AInsulation →
St. Francois County4A4AInsulation →
St. Louis County4A4AInsulation →
St. Louis (independent city)4A4AInsulation →
Ste. Genevieve County4A4AInsulation →
Stoddard County4A4AInsulation →
Stone County4A4AInsulation →
Sullivan County5A5AInsulation →
Taney County4A4AInsulation →
Texas County4A4AInsulation →
Vernon County4A4AInsulation →
Warren County4A4AInsulation →
Washington County4A4AInsulation →
Wayne County4A4AInsulation →
Webster County4A4AInsulation →
Worth County5A5AInsulation →
Wright County4A4AInsulation →

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 Missouri?

Missouri spans IECC climate zones 3A to 5A; zone 4A is the most common. Find your county in the table above, or search by ZIP code.

How much attic insulation do I need in Missouri?

In Missouri, the 2021 IECC calls for R-49 and R-60 in the attic, depending on the zone. The table near the top of this page lists each zone's minimums.

What energy code does Missouri use?

Missouri has no statewide residential energy code; cities and counties adopt their own, so check with your local building department. Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments.

More for Missouri: Last frost dates in Missouri · Missouri planting zones · Frost line depth by state