New York climate zones and HVAC design temperatures
New York spans 3 IECC climate zones. 63% of people live in zone 4A (mixed, humid). In New York, heating and cooling equipment is sized for 88°F in summer and 18°F in winter.
Design temperatures for major cities
| City | Zone | Summer 1% | Winter 99% | Water in |
|---|---|---|---|---|
| New York | 4A | 88°F | 18°F | 59°F |
| Buffalo | 5A | 85°F | 9°F | 53°F |
| Rochester | 5A | 87°F | 8°F | 53°F |
| Syracuse | 5A | 87°F | 5°F | 52°F |
| Albany | 5A | 87°F | 7°F | 53°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: 92°F (Richmond County); coldest winter design: -11°F (Essex County).
Typical equipment sizes in New York
One-story house with average insulation (R-13 walls, R-30 attic, double-pane windows), at New York'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 + 5 kW backup |
| 2,000 sq ft | 2.5 tons | 40,000 BTU | 3 tons + 5 kW backup |
| 2,500 sq ft | 3 tons | 40,000 BTU | 3.5 tons + 5 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 4A: mixed, humid (8 counties, 63% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Bronx County | 90°F | 19°F |
| Kings County | 88°F | 18°F |
| Nassau County | 87°F | 18°F |
| New York County | 88°F | 18°F |
| Queens County | 90°F | 19°F |
| Richmond County | 92°F | 17°F |
| Suffolk County | 86°F | 17°F |
| Westchester County | 87°F | 15°F |
Zone 5A: cool, humid (36 counties, 30% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Albany County | 87°F | 7°F |
| Allegany County | 82°F | 5°F |
| Broome County | 82°F | 5°F |
| Cattaraugus County | 79°F | 3°F |
| Cayuga County | 87°F | 5°F |
| Chautauqua County | 81°F | 7°F |
| Chemung County | 87°F | 5°F |
| Columbia County | 84°F | 4°F |
| Cortland County | 85°F | 5°F |
| Dutchess County | 89°F | 11°F |
| Erie County | 85°F | 9°F |
| Genesee County | 87°F | 8°F |
| Greene County | 87°F | 7°F |
| Livingston County | 88°F | 7°F |
| Monroe County | 87°F | 8°F |
| Niagara County | 86°F | 8°F |
| Onondaga County | 87°F | 5°F |
| Ontario County | 86°F | 8°F |
| Orange County | 87°F | 10°F |
| Orleans County | 87°F | 8°F |
| Oswego County | 86°F | 5°F |
| Putnam County | 87°F | 11°F |
| Rensselaer County | 87°F | 7°F |
| Rockland County | 87°F | 15°F |
| Saratoga County | 87°F | 7°F |
| Schenectady County | 87°F | 7°F |
| Schoharie County | 87°F | 7°F |
| Schuyler County | 87°F | 5°F |
| Seneca County | 86°F | 8°F |
| Steuben County | 87°F | 5°F |
| Tioga County | 82°F | 5°F |
| Tompkins County | 85°F | 5°F |
| Washington County | 85°F | 1°F |
| Wayne County | 87°F | 8°F |
| Wyoming County | 88°F | 7°F |
| Yates County | 86°F | 8°F |
Zone 6A: cold, humid (18 counties, 7% of people)
| County | Summer 1% | Winter 99% |
|---|---|---|
| Chenango County | 82°F | 5°F |
| Clinton County | 84°F | -1°F |
| Delaware County | 82°F | 5°F |
| Essex County | 81°F | -11°F |
| Franklin County | 81°F | -11°F |
| Fulton County | 87°F | 7°F |
| Hamilton County | 85°F | 1°F |
| Herkimer County | 85°F | 1°F |
| Jefferson County | 84°F | -4°F |
| Lewis County | 84°F | -3°F |
| Madison County | 87°F | 5°F |
| Montgomery County | 87°F | 7°F |
| Oneida County | 85°F | 1°F |
| Otsego County | 85°F | 1°F |
| St. Lawrence County | 84°F | -4°F |
| Sullivan County | 87°F | 10°F |
| Ulster County | 89°F | 11°F |
| Warren County | 85°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.