North Dakota Climate Zones by County
North Dakota's 53 counties span climate zones 6A to 7 under the 2021 International Energy Conservation Code (IECC). Zone 6A is the most common, with 37 of the 53. For reference, Fargo and Bismarck are in zone 6A and Minot is in 7.
Insulation minimums for each zone in North Dakota
| Zone | Counties | Attic | Wood-frame walls | Floors over unheated space | Basement walls |
|---|---|---|---|---|---|
| 6A | 37 | R-60 | R-30, or 20+5ci, or 13+10ci, or R-20ci | R-30 | R-15ci, or R-19, or 13+5ci |
| 7 | 16 | 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 North Dakota uses
North Dakota 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
14 counties moved one zone warmer in the 2021 map: Barnes County (7 → 6), Cass County (7 → 6), Eddy County (7 → 6), Foster County (7 → 6), Griggs County (7 → 6), Kidder County (7 → 6), McLean County (7 → 6), Mountrail County (7 → 6), Sheridan County (7 → 6), Steele County (7 → 6), Stutsman County (7 → 6), Traill County (7 → 6), and 2 more marked in the table below. If your town still enforces the 2018 or 2015 code, the older zone applies to permits.
Every county in North Dakota
| Name | Zone (2021) | Zone (2018) | Details |
|---|---|---|---|
| Adams County | 6A | 6A | Insulation → |
| Barnes County | 6A | 7 changed | Insulation → |
| Benson County | 7 | 7 | Insulation → |
| Billings County | 6A | 6A | Insulation → |
| Bottineau County | 7 | 7 | Insulation → |
| Bowman County | 6A | 6A | Insulation → |
| Burke County | 7 | 7 | Insulation → |
| Burleigh County | 6A | 6A | Insulation → |
| Cass County | 6A | 7 changed | Insulation → |
| Cavalier County | 7 | 7 | Insulation → |
| Dickey County | 6A | 6A | Insulation → |
| Divide County | 7 | 7 | Insulation → |
| Dunn County | 6A | 6A | Insulation → |
| Eddy County | 6A | 7 changed | Insulation → |
| Emmons County | 6A | 6A | Insulation → |
| Foster County | 6A | 7 changed | Insulation → |
| Golden Valley County | 6A | 6A | Insulation → |
| Grand Forks County | 7 | 7 | Insulation → |
| Grant County | 6A | 6A | Insulation → |
| Griggs County | 6A | 7 changed | Insulation → |
| Hettinger County | 6A | 6A | Insulation → |
| Kidder County | 6A | 7 changed | Insulation → |
| LaMoure County | 6A | 6A | Insulation → |
| Logan County | 6A | 6A | Insulation → |
| McHenry County | 7 | 7 | Insulation → |
| McIntosh County | 6A | 6A | Insulation → |
| McKenzie County | 6A | 6A | Insulation → |
| McLean County | 6A | 7 changed | Insulation → |
| Mercer County | 6A | 6A | Insulation → |
| Morton County | 6A | 6A | Insulation → |
| Mountrail County | 6A | 7 changed | Insulation → |
| Nelson County | 7 | 7 | Insulation → |
| Oliver County | 6A | 6A | Insulation → |
| Pembina County | 7 | 7 | Insulation → |
| Pierce County | 7 | 7 | Insulation → |
| Ramsey County | 7 | 7 | Insulation → |
| Ransom County | 6A | 6A | Insulation → |
| Renville County | 7 | 7 | Insulation → |
| Richland County | 6A | 6A | Insulation → |
| Rolette County | 7 | 7 | Insulation → |
| Sargent County | 6A | 6A | Insulation → |
| Sheridan County | 6A | 7 changed | Insulation → |
| Sioux County | 6A | 6A | Insulation → |
| Slope County | 6A | 6A | Insulation → |
| Stark County | 6A | 6A | Insulation → |
| Steele County | 6A | 7 changed | Insulation → |
| Stutsman County | 6A | 7 changed | Insulation → |
| Towner County | 7 | 7 | Insulation → |
| Traill County | 6A | 7 changed | Insulation → |
| Walsh County | 7 | 7 | Insulation → |
| Ward County | 7 | 7 | Insulation → |
| Wells County | 6A | 7 changed | Insulation → |
| Williams County | 6A | 7 changed | 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 North Dakota?
North Dakota spans IECC climate zones 6A to 7; zone 6A is the most common. Find your county in the table above, or search by ZIP code.
How much attic insulation do I need in North Dakota?
The 2021 IECC calls for R-60 in the attic everywhere in North Dakota.
What energy code does North Dakota use?
North Dakota 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 North Dakota: Last frost dates in North Dakota · North Dakota planting zones · Frost line depth by state