Nevada climate zones and HVAC design temperatures
Nevada spans 3 IECC climate zones. 73% of people live in zone 3B (warm, dry). In Las Vegas, heating and cooling equipment is sized for 108°F in summer and 37°F in winter.
Design temperatures for major cities
| City | Zone | Summer 1% | Winter 99% | Water in |
|---|---|---|---|---|
| Las Vegas | 3B | 108°F | 37°F | 73°F |
| Reno | 5B | 96°F | 22°F | 58°F |
| Carson City | 4B | 93°F | 18°F | 55°F |
| Elko | 5B | 95°F | 7°F | 51°F |
| Ely | 5B | 91°F | 3°F | 49°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: 108°F (Clark County); coldest winter design: 3°F (White Pine County).
Typical equipment sizes in Las Vegas
One-story house with average insulation (R-13 walls, R-30 attic, double-pane windows), at Las Vegas'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 | 2.5 tons | 40,000 BTU | 2.5 tons |
| 2,000 sq ft | 3 tons | 40,000 BTU | 3 tons |
| 2,500 sq ft | 4 tons | 40,000 BTU | 4 tons |
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 3B: warm, dry (1 county, 73% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Clark County | 108°F | 37°F |
Zone 4B: mixed, dry (7 counties, 7% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Carson City | 93°F | 18°F |
| Douglas County | 93°F | 10°F |
| Esmeralda County | 95°F | 17°F |
| Lincoln County | 104°F | 28°F |
| Lyon County | 93°F | 18°F |
| Mineral County | 98°F | 18°F |
| Nye County | 103°F | 32°F |
Zone 5B: cool, dry (9 counties, 20% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Churchill County | 98°F | 18°F |
| Elko County | 95°F | 7°F |
| Eureka County | 92°F | 4°F |
| Humboldt County | 98°F | 13°F |
| Lander County | 99°F | 14°F |
| Pershing County | 98°F | 13°F |
| Storey County | 96°F | 22°F |
| Washoe County | 96°F | 22°F |
| White Pine County | 91°F | 3°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.