Minnesota climate zones and HVAC design temperatures
Minnesota spans 3 IECC climate zones. 87% of people live in zone 6A (cold, humid). In Minneapolis, heating and cooling equipment is sized for 88°F in summer and -6°F in winter.
Design temperatures for major cities
| City | Zone | Summer 1% | Winter 99% | Water in |
|---|---|---|---|---|
| Minneapolis | 6A | 88°F | -6°F | 50°F |
| St. Paul | 6A | 87°F | -5°F | 50°F |
| Rochester | 6A | 85°F | -8°F | 48°F |
| Duluth | 7 | 82°F | -11°F | 44°F |
| St. Cloud | 6A | 86°F | -10°F | 47°F |
Summer: exceeded in 1% of hours. Winter: colder in only 1% of hours. Water in: estimated groundwater temperature for tankless water heater sizing. Computed for each county from NOAA hourly weather data, 2015-2024; see where our numbers come from. Hottest summer design in the state: 90°F (Lac qui Parle County); coldest winter design: -21°F (Koochiching County).
Typical equipment sizes in Minneapolis
One-story house with average insulation (R-13 walls, R-30 attic, double-pane windows), at Minneapolis's design temperatures. Your house can need more or less; use the calculators for yours.
| House | Central AC | Gas furnace (95% AFUE) | Heat pump |
|---|---|---|---|
| 1,500 sq ft | 2 tons | 40,000 BTU | 2 tons + 10 kW backup |
| 2,000 sq ft | 2.5 tons | 60,000 BTU | 2.5 tons + 15 kW backup |
| 2,500 sq ft | 3 tons | 60,000 BTU | 3.5 tons + 15 kW backup |
AC size calculator Furnace size calculator Heat pump size calculator
Climate zone by county
From the 2021 International Energy Conservation Code (IECC), as published by the U.S. Department of Energy. The zone sets the insulation and window requirements in the energy code; the number runs from 1 (hottest) to 8 (coldest), and the letter is A for moist, B for dry and C for marine.
Zone 5A: cool, humid (3 counties, 2% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Fillmore County | 84°F | -8°F |
| Houston County | 89°F | -3°F |
| Winona County | 86°F | -2°F |
Zone 6A: cold, humid (61 counties, 87% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Anoka County | 88°F | -6°F |
| Becker County | 84°F | -15°F |
| Benton County | 86°F | -10°F |
| Big Stone County | 88°F | -9°F |
| Blue Earth County | 86°F | -7°F |
| Brown County | 88°F | -9°F |
| Carver County | 88°F | -6°F |
| Chippewa County | 88°F | -9°F |
| Chisago County | 86°F | -8°F |
| Clay County | 88°F | -13°F |
| Cottonwood County | 88°F | -9°F |
| Dakota County | 87°F | -5°F |
| Dodge County | 84°F | -8°F |
| Douglas County | 86°F | -11°F |
| Faribault County | 87°F | -7°F |
| Freeborn County | 88°F | -6°F |
| Goodhue County | 88°F | -8°F |
| Grant County | 84°F | -13°F |
| Hennepin County | 88°F | -6°F |
| Isanti County | 88°F | -8°F |
| Jackson County | 86°F | -6°F |
| Kanabec County | 84°F | -9°F |
| Kandiyohi County | 88°F | -8°F |
| Lac qui Parle County | 90°F | -8°F |
| Le Sueur County | 86°F | -7°F |
| Lincoln County | 88°F | -8°F |
| Lyon County | 88°F | -8°F |
| Martin County | 87°F | -7°F |
| McLeod County | 87°F | -8°F |
| Meeker County | 88°F | -8°F |
| Mille Lacs County | 88°F | -9°F |
| Morrison County | 84°F | -11°F |
| Mower County | 86°F | -6°F |
| Murray County | 88°F | -6°F |
| Nicollet County | 86°F | -7°F |
| Nobles County | 87°F | -7°F |
| Olmsted County | 85°F | -8°F |
| Otter Tail County | 84°F | -13°F |
| Pipestone County | 86°F | -6°F |
| Pope County | 86°F | -11°F |
| Ramsey County | 87°F | -5°F |
| Redwood County | 88°F | -8°F |
| Renville County | 86°F | -8°F |
| Rice County | 86°F | -8°F |
| Rock County | 86°F | -6°F |
| Scott County | 88°F | -6°F |
| Sherburne County | 88°F | -9°F |
| Sibley County | 87°F | -8°F |
| Stearns County | 86°F | -10°F |
| Steele County | 86°F | -8°F |
| Stevens County | 88°F | -11°F |
| Swift County | 88°F | -11°F |
| Todd County | 84°F | -17°F |
| Traverse County | 88°F | -9°F |
| Wabasha County | 88°F | -8°F |
| Waseca County | 84°F | -6°F |
| Washington County | 87°F | -5°F |
| Watonwan County | 88°F | -8°F |
| Wilkin County | 86°F | -13°F |
| Wright County | 86°F | -8°F |
| Yellow Medicine County | 89°F | -8°F |
Zone 7: very cold (23 counties, 11% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Aitkin County | 82°F | -15°F |
| Beltrami County | 83°F | -18°F |
| Carlton County | 82°F | -11°F |
| Cass County | 82°F | -17°F |
| Clearwater County | 82°F | -20°F |
| Cook County | 73°F | -6°F |
| Crow Wing County | 86°F | -13°F |
| Hubbard County | 85°F | -18°F |
| Itasca County | 82°F | -15°F |
| Kittson County | 86°F | -18°F |
| Koochiching County | 83°F | -21°F |
| Lake County | 82°F | -9°F |
| Lake of the Woods County | 83°F | -19°F |
| Mahnomen County | 82°F | -20°F |
| Marshall County | 84°F | -17°F |
| Norman County | 88°F | -13°F |
| Pennington County | 84°F | -17°F |
| Pine County | 84°F | -9°F |
| Polk County | 84°F | -17°F |
| Red Lake County | 84°F | -17°F |
| Roseau County | 84°F | -17°F |
| St. Louis County | 82°F | -11°F |
| Wadena County | 84°F | -17°F |
Climate data as of 2026-10. Design temperatures may differ by a few degrees from the ACCA Manual J tables your contractor uses; winter values run a little warmer because recent winters have been milder.