Climate zones and design temperatures by state
Heating and cooling equipment is sized for your climate: the IECC climate zone and the summer and winter design temperatures. Pick a state for every county's zone, major cities and typical equipment sizes.
| State | Main zone | Largest city | Summer 1% | Winter 99% | AC, 2,000 sq ft |
|---|---|---|---|---|---|
| Alabama | 3A | Huntsville | 91°F | 23°F | 3 tons |
| Alaska | 7 | Anchorage | 72°F | -4°F | 2 tons |
| Arizona | 2B | Phoenix | 110°F | 43°F | 3 tons |
| Arkansas | 3A | Little Rock | 95°F | 25°F | 3 tons |
| California | 3B | Los Angeles | 86°F | 47°F | 2.5 tons |
| Colorado | 5B | Denver | 92°F | 7°F | 2.5 tons |
| Connecticut | 5A | Bridgeport | 86°F | 16°F | 2.5 tons |
| Delaware | 4A | Wilmington | 90°F | 18°F | 2.5 tons |
| District of Columbia | 4A | Washington | 92°F | 23°F | 2.5 tons |
| Florida | 2A | Jacksonville | 94°F | 42°F | 3 tons |
| Georgia | 3A | Atlanta | 92°F | 27°F | 3 tons |
| Hawaii | 1A | Honolulu | 89°F | 66°F | 3 tons |
| Idaho | 5B | Boise | 97°F | 16°F | 2.5 tons |
| Illinois | 5A | Chicago | 89°F | 6°F | 2.5 tons |
| Indiana | 5A | Indianapolis | 89°F | 9°F | 2.5 tons |
| Iowa | 5A | Des Moines | 90°F | 0°F | 2.5 tons |
| Kansas | 4A | Wichita | 97°F | 13°F | 3 tons |
| Kentucky | 4A | Louisville | 91°F | 16°F | 2.5 tons |
| Louisiana | 2A | New Orleans | 93°F | 40°F | 3 tons |
| Maine | 6A | Portland | 84°F | 7°F | 2.5 tons |
| Maryland | 4A | Baltimore | 92°F | 19°F | 2.5 tons |
| Massachusetts | 5A | Boston | 88°F | 14°F | 2.5 tons |
| Michigan | 5A | Detroit | 88°F | 9°F | 2.5 tons |
| Minnesota | 6A | Minneapolis | 88°F | -6°F | 2.5 tons |
| Mississippi | 3A | Jackson | 94°F | 29°F | 3 tons |
| Missouri | 4A | Kansas City | 92°F | 9°F | 2.5 tons |
| Montana | 6B | Billings | 92°F | -4°F | 2.5 tons |
| Nebraska | 5A | Omaha | 92°F | 4°F | 2.5 tons |
| Nevada | 3B | Las Vegas | 108°F | 37°F | 3 tons |
| New Hampshire | 5A | Manchester | 90°F | 9°F | 2.5 tons |
| New Jersey | 4A | Newark | 92°F | 17°F | 2.5 tons |
| New Mexico | 4B | Albuquerque | 94°F | 23°F | 2.5 tons |
| New York | 4A | New York | 88°F | 18°F | 2.5 tons |
| North Carolina | 3A | Charlotte | 93°F | 27°F | 3 tons |
| North Dakota | 6A | Fargo | 88°F | -13°F | 2.5 tons |
| Ohio | 5A | Columbus | 89°F | 11°F | 2.5 tons |
| Oklahoma | 3A | Oklahoma City | 97°F | 19°F | 3 tons |
| Oregon | 4C | Portland | 90°F | 30°F | 2.5 tons |
| Pennsylvania | 4A | Philadelphia | 92°F | 18°F | 2.5 tons |
| Rhode Island | 5A | Providence | 86°F | 11°F | 2.5 tons |
| South Carolina | 3A | Charleston | 92°F | 32°F | 3 tons |
| South Dakota | 6A | Sioux Falls | 90°F | -4°F | 2.5 tons |
| Tennessee | 3A | Nashville | 93°F | 21°F | 3 tons |
| Texas | 2A | Houston | 97°F | 37°F | 3 tons |
| Utah | 5B | Salt Lake City | 98°F | 20°F | 3 tons |
| Vermont | 6A | Burlington | 87°F | 0°F | 2.5 tons |
| Virginia | 4A | Virginia Beach | 92°F | 27°F | 3 tons |
| Washington | 4C | Seattle | 85°F | 30°F | 2.5 tons |
| West Virginia | 4A | Charleston | 89°F | 16°F | 2.5 tons |
| Wisconsin | 5A | Milwaukee | 87°F | 4°F | 2.5 tons |
| Wyoming | 6B | Cheyenne | 88°F | 3°F | 2.5 tons |
Main zone: the zone most of the state's people live in. AC: a one-story house with average insulation at the largest city's design temperatures. See where our numbers come from.