Wyoming Climate Zones by County
Wyoming's 23 counties span climate zones 5B to 7 under the 2021 International Energy Conservation Code (IECC). Zone 6B is the most common, with 17 of the 23. For reference, Cheyenne is in zone 5B, Casper is in 6B and Jackson is in 7.
Insulation minimums for each zone in Wyoming
| Zone | Counties | Attic | Wood-frame walls | Floors over unheated space | Basement walls |
|---|---|---|---|---|---|
| 5B | 3 | R-60 | R-30, or 20+5ci, or 13+10ci, or R-20ci | R-30 | R-15ci, or R-19, or 13+5ci |
| 6B | 17 | R-60 | R-30, or 20+5ci, or 13+10ci, or R-20ci | R-30 | R-15ci, or R-19, or 13+5ci |
| 7 | 3 | R-60 | R-30, or 20+5ci, or 13+10ci, or R-20ci | R-38 | R-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 Wyoming uses
Wyoming 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
One county moved one zone warmer in the 2021 map: Laramie County (6 → 5). If your town still enforces the 2018 or 2015 code, the older zone applies to permits.
Every county in Wyoming
| Name | Zone (2021) | Zone (2018) | Details |
|---|---|---|---|
| Albany County | 6B | 6B | Insulation → |
| Big Horn County | 6B | 6B | Insulation → |
| Campbell County | 6B | 6B | Insulation → |
| Carbon County | 6B | 6B | Insulation → |
| Converse County | 6B | 6B | Insulation → |
| Crook County | 6B | 6B | Insulation → |
| Fremont County | 6B | 6B | Insulation → |
| Goshen County | 5B | 5B | Insulation → |
| Hot Springs County | 6B | 6B | Insulation → |
| Johnson County | 6B | 6B | Insulation → |
| Laramie County | 5B | 6B changed | Insulation → |
| Lincoln County | 7 | 7 | Insulation → |
| Natrona County | 6B | 6B | Insulation → |
| Niobrara County | 6B | 6B | Insulation → |
| Park County | 6B | 6B | Insulation → |
| Platte County | 5B | 5B | Insulation → |
| Sheridan County | 6B | 6B | Insulation → |
| Sublette County | 7 | 7 | Insulation → |
| Sweetwater County | 6B | 6B | Insulation → |
| Teton County | 7 | 7 | Insulation → |
| Uinta County | 6B | 6B | Insulation → |
| Washakie County | 6B | 6B | Insulation → |
| Weston County | 6B | 6B | Insulation → |
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 Wyoming?
Wyoming spans IECC climate zones 5B to 7; zone 6B is the most common. Find your county in the table above, or search by ZIP code.
How much attic insulation do I need in Wyoming?
The 2021 IECC calls for R-60 in the attic everywhere in Wyoming.
What energy code does Wyoming use?
Wyoming 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.
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