New Mexico Climate Zones by County
New Mexico's 33 counties span climate zones 3B to 5B under the 2021 International Energy Conservation Code (IECC). Zone 4B is the most common, with 13 of the 33. For reference, Las Cruces is in zone 3B, Albuquerque is in 4B and Santa Fe is in 5B.
Insulation minimums for each zone in New Mexico
| Zone | Counties | Attic | Wood-frame walls | Floors over unheated space | Basement walls |
|---|---|---|---|---|---|
| 3B | 8 | R-49 | R-20, or 13+5ci, or R-15ci | R-19 | R-5ci or R-13 |
| 4B | 13 | R-60 | R-30, or 20+5ci, or 13+10ci, or R-20ci | R-19 | R-10ci or R-13 |
| 5B | 12 | R-60 | R-30, or 20+5ci, or 13+10ci, or R-20ci | R-30 | 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 New Mexico uses
New Mexico enforces the 2021 IECC with amendments for homes (in effect since Jan 2024). 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
Two counties moved one zone warmer in the 2021 map: Catron County (5 → 4), Sierra County (4 → 3). If your town still enforces the 2018 or 2015 code, the older zone applies to permits.
Every county in New Mexico
| Name | Zone (2021) | Zone (2018) | Details |
|---|---|---|---|
| Bernalillo County | 4B | 4B | Insulation → |
| Catron County | 4B | 5B changed | Insulation → |
| Chaves County | 3B | 3B | Insulation → |
| Cibola County | 4B | 4B | Insulation → |
| Colfax County | 5B | 5B | Insulation → |
| Curry County | 4B | 4B | Insulation → |
| DeBaca County | 4B | 4B | Insulation → |
| Dona Ana County | 3B | 3B | Insulation → |
| Eddy County | 3B | 3B | Insulation → |
| Grant County | 4B | 4B | Insulation → |
| Guadalupe County | 4B | 4B | Insulation → |
| Harding County | 5B | 5B | Insulation → |
| Hidalgo County | 3B | 3B | Insulation → |
| Lea County | 3B | 3B | Insulation → |
| Lincoln County | 4B | 4B | Insulation → |
| Los Alamos County | 5B | 5B | Insulation → |
| Luna County | 3B | 3B | Insulation → |
| McKinley County | 5B | 5B | Insulation → |
| Mora County | 5B | 5B | Insulation → |
| Otero County | 3B | 3B | Insulation → |
| Quay County | 4B | 4B | Insulation → |
| Rio Arriba County | 5B | 5B | Insulation → |
| Roosevelt County | 4B | 4B | Insulation → |
| San Juan County | 5B | 5B | Insulation → |
| San Miguel County | 5B | 5B | Insulation → |
| Sandoval County | 5B | 5B | Insulation → |
| Santa Fe County | 5B | 5B | Insulation → |
| Sierra County | 3B | 4B changed | Insulation → |
| Socorro County | 4B | 4B | Insulation → |
| Taos County | 5B | 5B | Insulation → |
| Torrance County | 5B | 5B | Insulation → |
| Union County | 4B | 4B | Insulation → |
| Valencia County | 4B | 4B | 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 New Mexico?
New Mexico spans IECC climate zones 3B to 5B; zone 4B is the most common. Find your county in the table above, or search by ZIP code.
How much attic insulation do I need in New Mexico?
In New Mexico, 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 New Mexico use?
New Mexico enforces the 2021 IECC with amendments for homes (in effect since Jan 2024). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments.
More for New Mexico: Last frost dates in New Mexico · New Mexico planting zones · Frost line depth by state