Nebraska climate zones and HVAC design temperatures
All of Nebraska is in IECC climate zone 5A (cool, humid). In Omaha, heating and cooling equipment is sized for 92°F in summer and 4°F in winter.
Design temperatures for major cities
| City | Zone | Summer 1% | Winter 99% | Water in |
|---|---|---|---|---|
| Omaha | 5A | 92°F | 4°F | 56°F |
| Lincoln | 5A | 93°F | 3°F | 56°F |
| Grand Island | 5A | 93°F | 2°F | 54°F |
| Kearney | 5A | 91°F | 3°F | 54°F |
| North Platte | 5A | 94°F | 2°F | 52°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: 96°F (Chase County); coldest winter design: -3°F (Cedar County).
Typical equipment sizes in Omaha
One-story house with average insulation (R-13 walls, R-30 attic, double-pane windows), at Omaha'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 | 2.5 tons + 8 kW backup |
| 2,000 sq ft | 2.5 tons | 60,000 BTU | 3 tons + 8 kW backup |
| 2,500 sq ft | 3 tons | 60,000 BTU | 3.5 tons + 10 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 (93 counties, 100% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Adams County | 92°F | 3°F |
| Antelope County | 90°F | 0°F |
| Arthur County | 95°F | 3°F |
| Banner County | 95°F | 1°F |
| Blaine County | 93°F | 1°F |
| Boone County | 90°F | 0°F |
| Box Butte County | 93°F | -2°F |
| Boyd County | 91°F | -1°F |
| Brown County | 91°F | -1°F |
| Buffalo County | 91°F | 3°F |
| Burt County | 92°F | 0°F |
| Butler County | 91°F | 1°F |
| Cass County | 91°F | 3°F |
| Cedar County | 91°F | -3°F |
| Chase County | 96°F | 3°F |
| Cherry County | 95°F | -2°F |
| Cheyenne County | 94°F | 1°F |
| Clay County | 92°F | 3°F |
| Colfax County | 91°F | 1°F |
| Cuming County | 91°F | -2°F |
| Custer County | 91°F | 1°F |
| Dakota County | 90°F | -1°F |
| Dawes County | 96°F | -2°F |
| Dawson County | 92°F | 3°F |
| Deuel County | 95°F | 3°F |
| Dixon County | 91°F | -2°F |
| Dodge County | 92°F | 3°F |
| Douglas County | 92°F | 4°F |
| Dundy County | 96°F | 5°F |
| Fillmore County | 90°F | 1°F |
| Franklin County | 91°F | 4°F |
| Frontier County | 96°F | 4°F |
| Furnas County | 91°F | 4°F |
| Gage County | 93°F | 4°F |
| Garden County | 95°F | 3°F |
| Garfield County | 91°F | 0°F |
| Gosper County | 92°F | 3°F |
| Grant County | 93°F | -2°F |
| Greeley County | 91°F | 0°F |
| Hall County | 93°F | 2°F |
| Hamilton County | 91°F | 2°F |
| Harlan County | 91°F | 4°F |
| Hayes County | 96°F | 3°F |
| Hitchcock County | 96°F | 4°F |
| Holt County | 91°F | -1°F |
| Hooker County | 93°F | 1°F |
| Howard County | 93°F | 2°F |
| Jefferson County | 93°F | 4°F |
| Johnson County | 91°F | 3°F |
| Kearney County | 91°F | 3°F |
| Keith County | 95°F | 3°F |
| Keya Paha County | 91°F | -1°F |
| Kimball County | 92°F | 2°F |
| Knox County | 91°F | -3°F |
| Lancaster County | 93°F | 3°F |
| Lincoln County | 94°F | 2°F |
| Logan County | 94°F | 2°F |
| Loup County | 91°F | 0°F |
| Madison County | 91°F | 0°F |
| McPherson County | 94°F | 2°F |
| Merrick County | 91°F | 2°F |
| Morrill County | 95°F | 1°F |
| Nance County | 90°F | 0°F |
| Nemaha County | 91°F | 3°F |
| Nuckolls County | 93°F | 5°F |
| Otoe County | 91°F | 3°F |
| Pawnee County | 92°F | 4°F |
| Perkins County | 95°F | 3°F |
| Phelps County | 91°F | 4°F |
| Pierce County | 91°F | 0°F |
| Platte County | 91°F | 1°F |
| Polk County | 90°F | 1°F |
| Red Willow County | 96°F | 4°F |
| Richardson County | 92°F | 4°F |
| Rock County | 91°F | -1°F |
| Saline County | 93°F | 3°F |
| Sarpy County | 92°F | 4°F |
| Saunders County | 91°F | 2°F |
| Scotts Bluff County | 95°F | 1°F |
| Seward County | 93°F | 3°F |
| Sheridan County | 95°F | -3°F |
| Sherman County | 91°F | 0°F |
| Sioux County | 94°F | 0°F |
| Stanton County | 91°F | 0°F |
| Thayer County | 93°F | 5°F |
| Thomas County | 93°F | 1°F |
| Thurston County | 90°F | -1°F |
| Valley County | 91°F | 0°F |
| Washington County | 90°F | 2°F |
| Wayne County | 91°F | -2°F |
| Webster County | 92°F | 3°F |
| Wheeler County | 90°F | 0°F |
| York County | 90°F | 1°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.