Guide to U.S. Climate & Hardiness Zones
It's a common point of confusion: "Climate Zones" for building are different from "Plant Hardiness Zones" for gardening. This guide clarifies the two and directs you to the right official resource.
DOE Building Climate Zones
For projects like insulation, new windows, or HVAC sizing, you MUST use the Department of Energy (DOE) climate zones. These are based on heating and cooling needs and are essential for building code compliance and energy efficiency.
Official Government Lookup Tools
The most reliable way to find your building zone is by using an official county-by-county or zip code lookup tool. The general map can be misleading.
- PNNL Climate Zone Lookup (Recommended)
The Pacific Northwest National Laboratory (PNNL) offers a fast, easy-to-use lookup tool by county for finding your specific building climate zone.
- U.S. Department of Energy (DOE)
The official source for state-by-state building energy code information, including detailed maps and requirements.
USDA Plant Hardiness Zones
For gardening and choosing plants that will survive the winter, use the USDA Plant Hardiness Zone Map. It is based on the average annual minimum winter temperature and is not suitable for building purposes.
Official Government Resource
- USDA Plant Hardiness Zone Map
The official interactive map. Enter your ZIP code to find your exact hardiness zone for planting.
DOE Climate Zone General Breakdown
To determine your building zone with certainty, use the official lookup tools listed above. The table below provides a general, non-authoritative overview.
| Zone | Climate Type | General Locations |
|---|---|---|
| Zone 1 | Hot-Humid | South Florida, Hawaii, Guam, Puerto Rico, Virgin Islands |
| Zone 2 | Hot-Dry / Mixed-Humid | Most of Florida, south Texas, southern Louisiana, southern Arizona |
| Zone 3 | Warm-Humid / Warm-Dry | The Southeast, coastal California, most of Texas and Arizona |
| Zone 4 | Mixed-Humid / Mixed-Dry | Mid-Atlantic, Pacific Northwest, parts of California, the Midwest |
| Zone 5 | Cool-Humid / Cool-Dry | The Northeast, Midwest, and the Rocky Mountains |
| Zone 6 | Cold-Humid / Cold-Dry | Northern Midwest, New England, northern Rockies |
| Zone 7 | Very-Cold | Northern Minnesota, Wisconsin, North Dakota, Maine, high elevations |
| Zone 8 | Subarctic | Most of Alaska |