Climate zones by state

Texas Climate Zones by County

Texas's 254 counties span climate zones 1A to 4B under the 2021 International Energy Conservation Code (IECC). Zone 2A is the most common, with 81 of the 254. For reference, Houston and Dallas are in zone 2A, Plano is in 3A, El Paso is in 3B and Amarillo is in 4B.

Insulation minimums for each zone in Texas

ZoneCountiesAtticWood-frame wallsFloors over unheated spaceBasement walls
1A3R-30R-13, or R-10ciR-13None required
2A81R-49R-13, or R-10ciR-13None required
2B14R-49R-13, or R-10ciR-13None required
3A58R-49R-20, or 13+5ci, or R-15ciR-19R-5ci or R-13
3B70R-49R-20, or 13+5ci, or R-15ciR-19R-5ci or R-13
4B28R-60R-30, or 20+5ci, or 13+10ci, or R-20ciR-19R-10ci 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 Texas uses

Texas enforces the 2015 IECC for homes (in effect since Sep 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

Eight counties moved one zone warmer in the 2021 map: Cameron County (2 → 1), Dallas County (3 → 2), Ellis County (3 → 2), Hidalgo County (2 → 1), Johnson County (3 → 2), Navarro County (3 → 2), Tarrant County (3 → 2), Willacy County (2 → 1). If your town still enforces the 2018 or 2015 code, the older zone applies to permits.

Every county in Texas

NameZone (2021)Zone (2018)Details
Anderson County2A2AInsulation →
Andrews County3B3BInsulation →
Angelina County2A2AInsulation →
Aransas County2A2AInsulation →
Archer County3A3AInsulation →
Armstrong County4B4BInsulation →
Atascosa County2A2AInsulation →
Austin County2A2AInsulation →
Bailey County4B4BInsulation →
Bandera County2B2BInsulation →
Bastrop County2A2AInsulation →
Baylor County3B3BInsulation →
Bee County2A2AInsulation →
Bell County2A2AInsulation →
Bexar County2A2AInsulation →
Blanco County3A3AInsulation →
Borden County3B3BInsulation →
Bosque County2A2AInsulation →
Bowie County3A3AInsulation →
Brazoria County2A2AInsulation →
Brazos County2A2AInsulation →
Brewster County3B3BInsulation →
Briscoe County4B4BInsulation →
Brooks County2A2AInsulation →
Brown County3A3AInsulation →
Burleson County2A2AInsulation →
Burnet County3A3AInsulation →
Caldwell County2A2AInsulation →
Calhoun County2A2AInsulation →
Callahan County3B3BInsulation →
Cameron County1A2A changedInsulation →
Camp County3A3AInsulation →
Carson County4B4BInsulation →
Cass County3A3AInsulation →
Castro County4B4BInsulation →
Chambers County2A2AInsulation →
Cherokee County2A2AInsulation →
Childress County3B3BInsulation →
Clay County3A3AInsulation →
Cochran County4B4BInsulation →
Coke County3B3BInsulation →
Coleman County3B3BInsulation →
Collin County3A3AInsulation →
Collingsworth County3B3BInsulation →
Colorado County2A2AInsulation →
Comal County2A2AInsulation →
Comanche County3A3AInsulation →
Concho County3B3BInsulation →
Cooke County3A3AInsulation →
Coryell County2A2AInsulation →
Cottle County3B3BInsulation →
Crane County3B3BInsulation →
Crockett County3B3BInsulation →
Crosby County3B3BInsulation →
Culberson County3B3BInsulation →
Dallam County4B4BInsulation →
Dallas County2A3A changedInsulation →
Dawson County3B3BInsulation →
Deaf Smith County4B4BInsulation →
Delta County3A3AInsulation →
Denton County3A3AInsulation →
DeWitt County2A2AInsulation →
Dickens County3B3BInsulation →
Dimmit County2B2BInsulation →
Donley County4B4BInsulation →
Duval County2A2AInsulation →
Eastland County3A3AInsulation →
Ector County3B3BInsulation →
Edwards County2B2BInsulation →
El Paso County3B3BInsulation →
Ellis County2A3A changedInsulation →
Erath County3A3AInsulation →
Falls County2A2AInsulation →
Fannin County3A3AInsulation →
Fayette County2A2AInsulation →
Fisher County3B3BInsulation →
Floyd County4B4BInsulation →
Foard County3B3BInsulation →
Fort Bend County2A2AInsulation →
Franklin County3A3AInsulation →
Freestone County2A2AInsulation →
Frio County2B2BInsulation →
Gaines County3B3BInsulation →
Galveston County2A2AInsulation →
Garza County3B3BInsulation →
Gillespie County3A3AInsulation →
Glasscock County3B3BInsulation →
Goliad County2A2AInsulation →
Gonzales County2A2AInsulation →
Gray County4B4BInsulation →
Grayson County3A3AInsulation →
Gregg County3A3AInsulation →
Grimes County2A2AInsulation →
Guadalupe County2A2AInsulation →
Hale County4B4BInsulation →
Hall County3B3BInsulation →
Hamilton County3A3AInsulation →
Hansford County4B4BInsulation →
Hardeman County3B3BInsulation →
Hardin County2A2AInsulation →
Harris County2A2AInsulation →
Harrison County3A3AInsulation →
Hartley County4B4BInsulation →
Haskell County3B3BInsulation →
Hays County2A2AInsulation →
Hemphill County3B3BInsulation →
Henderson County3A3AInsulation →
Hidalgo County1A2A changedInsulation →
Hill County2A2AInsulation →
Hockley County4B4BInsulation →
Hood County3A3AInsulation →
Hopkins County3A3AInsulation →
Houston County2A2AInsulation →
Howard County3B3BInsulation →
Hudspeth County3B3BInsulation →
Hunt County3A3AInsulation →
Hutchinson County4B4BInsulation →
Irion County3B3BInsulation →
Jack County3A3AInsulation →
Jackson County2A2AInsulation →
Jasper County2A2AInsulation →
Jeff Davis County3B3BInsulation →
Jefferson County2A2AInsulation →
Jim Hogg County2A2AInsulation →
Jim Wells County2A2AInsulation →
Johnson County2A3A changedInsulation →
Jones County3B3BInsulation →
Karnes County2A2AInsulation →
Kaufman County3A3AInsulation →
Kendall County3A3AInsulation →
Kenedy County2A2AInsulation →
Kent County3B3BInsulation →
Kerr County3B3BInsulation →
Kimble County3B3BInsulation →
King County3B3BInsulation →
Kinney County2B2BInsulation →
Kleberg County2A2AInsulation →
Knox County3B3BInsulation →
La Salle County2B2BInsulation →
Lamar County3A3AInsulation →
Lamb County4B4BInsulation →
Lampasas County3A3AInsulation →
Lavaca County2A2AInsulation →
Lee County2A2AInsulation →
Leon County2A2AInsulation →
Liberty County2A2AInsulation →
Limestone County2A2AInsulation →
Lipscomb County4B4BInsulation →
Live Oak County2A2AInsulation →
Llano County3A3AInsulation →
Loving County3B3BInsulation →
Lubbock County3B3BInsulation →
Lynn County3B3BInsulation →
Madison County2A2AInsulation →
Marion County3A3AInsulation →
Martin County3B3BInsulation →
Mason County3B3BInsulation →
Matagorda County2A2AInsulation →
Maverick County2B2BInsulation →
McCulloch County3B3BInsulation →
McLennan County2A2AInsulation →
McMullen County2A2AInsulation →
Medina County2B2BInsulation →
Menard County3B3BInsulation →
Midland County3B3BInsulation →
Milam County2A2AInsulation →
Mills County3A3AInsulation →
Mitchell County3B3BInsulation →
Montague County3A3AInsulation →
Montgomery County2A2AInsulation →
Moore County4B4BInsulation →
Morris County3A3AInsulation →
Motley County3B3BInsulation →
Nacogdoches County3A3AInsulation →
Navarro County2A3A changedInsulation →
Newton County2A2AInsulation →
Nolan County3B3BInsulation →
Nueces County2A2AInsulation →
Ochiltree County4B4BInsulation →
Oldham County4B4BInsulation →
Orange County2A2AInsulation →
Palo Pinto County3A3AInsulation →
Panola County3A3AInsulation →
Parker County3A3AInsulation →
Parmer County4B4BInsulation →
Pecos County3B3BInsulation →
Polk County2A2AInsulation →
Potter County4B4BInsulation →
Presidio County3B3BInsulation →
Rains County3A3AInsulation →
Randall County4B4BInsulation →
Reagan County3B3BInsulation →
Real County2B2BInsulation →
Red River County3A3AInsulation →
Reeves County3B3BInsulation →
Refugio County2A2AInsulation →
Roberts County4B4BInsulation →
Robertson County2A2AInsulation →
Rockwall County3A3AInsulation →
Runnels County3B3BInsulation →
Rusk County3A3AInsulation →
Sabine County3A3AInsulation →
San Augustine County3A3AInsulation →
San Jacinto County2A2AInsulation →
San Patricio County2A2AInsulation →
San Saba County3A3AInsulation →
Schleicher County3B3BInsulation →
Scurry County3B3BInsulation →
Shackelford County3B3BInsulation →
Shelby County3A3AInsulation →
Sherman County4B4BInsulation →
Smith County3A3AInsulation →
Somervell County3A3AInsulation →
Starr County2A2AInsulation →
Stephens County3A3AInsulation →
Sterling County3B3BInsulation →
Stonewall County3B3BInsulation →
Sutton County3B3BInsulation →
Swisher County4B4BInsulation →
Tarrant County2A3A changedInsulation →
Taylor County3B3BInsulation →
Terrell County3B3BInsulation →
Terry County3B3BInsulation →
Throckmorton County3B3BInsulation →
Titus County3A3AInsulation →
Tom Green County3B3BInsulation →
Travis County2A2AInsulation →
Trinity County2A2AInsulation →
Tyler County2A2AInsulation →
Upshur County3A3AInsulation →
Upton County3B3BInsulation →
Uvalde County2B2BInsulation →
Val Verde County2B2BInsulation →
Van Zandt County3A3AInsulation →
Victoria County2A2AInsulation →
Walker County2A2AInsulation →
Waller County2A2AInsulation →
Ward County3B3BInsulation →
Washington County2A2AInsulation →
Webb County2B2BInsulation →
Wharton County2A2AInsulation →
Wheeler County3B3BInsulation →
Wichita County3A3AInsulation →
Wilbarger County3B3BInsulation →
Willacy County1A2A changedInsulation →
Williamson County2A2AInsulation →
Wilson County2A2AInsulation →
Winkler County3B3BInsulation →
Wise County3A3AInsulation →
Wood County3A3AInsulation →
Yoakum County4B4BInsulation →
Young County3A3AInsulation →
Zapata County2B2BInsulation →
Zavala County2B2BInsulation →

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 Texas?

Texas spans IECC climate zones 1A to 4B; zone 2A is the most common. Find your county in the table above, or search by ZIP code.

How much attic insulation do I need in Texas?

In Texas, the 2021 IECC calls for R-30, 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 Texas use?

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

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