How-to guide
Thermostat Settings by US Climate Zone: Setbacks and Lockouts
By Ismail Farooq · Updated 2026-10-30
The same thermostat behaves very differently in Miami and Minneapolis. Smart thermostats ship with settings that suit an average climate, and the defaults that matter most, like how far to set back overnight and when a heat pump is allowed to use electric backup heat, are worth adjusting for where you live. This guide uses the climate zones from the US Department of Energy’s building energy codes (IECC), which divide the country into zones 1 (hottest) to 8 (coldest), plus a letter for moist (A), dry (B) or marine (C).
Find your zone
Zones follow county lines, and many states span more than one, so these are examples. DOE’s Building America climate zone map lists every county, and our thermostat settings by state pages list the zones and common heating in each state.
| Zone | Climate | Example places |
|---|---|---|
| 1 | Very hot, humid | Miami and the Florida Keys, Hawaii |
| 2 | Hot (humid 2A, dry 2B) | Houston, New Orleans, Orlando, Tampa (2A); Phoenix, Tucson (2B) |
| 3 | Warm (3A, 3B, 3C) | Atlanta, Dallas, Charlotte, Memphis (3A); Las Vegas, Los Angeles inland (3B); San Francisco (3C) |
| 4 | Mixed (4A, 4B, 4C) | New York City, Washington DC, Nashville, St. Louis, Kansas City (4A); Albuquerque (4B); Seattle, Portland (4C) |
| 5 | Cool (5A, 5B) | Chicago, Boston, Detroit, Cleveland, Pittsburgh (5A); Denver, Salt Lake City, Boise (5B) |
| 6 | Cold (6A, 6B) | Minneapolis, Burlington VT, much of Wisconsin, Maine and upstate New York (6A); Helena MT and mountain areas (6B) |
| 7 | Very cold | Duluth and northern Minnesota, northern Maine, northern Wisconsin, Anchorage |
| 8 | Subarctic | Fairbanks and interior Alaska |
Setpoints and setbacks everywhere
DOE’s guidance is a good baseline in every zone: about 68 °F in winter while you’re home and awake, and about 78 °F in summer when you’re home, with the temperature set back while you sleep or are out. Setting back 7 to 10 °F for 8 hours a day can save up to about 10% a year on heating and cooling. The rules below change how deep and how quickly you should do that with each kind of system.
- Furnace or boiler: deep setbacks are fine. The heat comes back quickly, and a smart thermostat’s early-start feature times it for you.
- Heat pump: keep winter setbacks small (2 to 4 °F) or let the thermostat’s smart recovery handle it. A big jump in setpoint on a cold morning brings on aux heat, which costs far more to run than the heat pump and can wipe out the saving.
- Electric baseboard: setbacks save money in every zone, room by room. See baseboard thermostat wiring for smart options.
Heat pump lockout starting points
Two settings decide how a heat pump and its backup share the work. Aux heat lockout (called “aux heat max outdoor temperature” on ecobee) stops electric strips from running above a set outdoor temperature. Compressor lockout (“compressor min outdoor temperature”) stops the heat pump below a set temperature, and matters mainly on dual-fuel systems with a gas furnace backup. Both need the thermostat to know the outdoor temperature, from an outdoor sensor or a weather service over Wi-Fi.
| Zone | Aux heat lockout (electric strips) | Compressor lockout (dual fuel) |
|---|---|---|
| 1–2 | About 40 °F. Aux heat should almost never be needed. | Rarely needed |
| 3 | 35–40 °F | Around 25–35 °F, by gas vs electricity price |
| 4 | 30–35 °F | Around 25–35 °F |
| 5 | 25–35 °F for a standard heat pump; lower for a cold-climate model | Around 20–35 °F |
| 6–8 | Set from the heat pump’s rated output at low temperatures; cold-climate models often run well below 10 °F | Often 0–25 °F, from the installer’s balance point |
These are starting points, not rules. Your installer’s balance point, the outdoor temperature where the heat pump alone can no longer keep up, is the number to use if you have it. If the house can’t hold temperature on the coldest days, raise the aux lockout a few degrees. If aux heat runs on mild days, lower it. Aux heat running too much goes through the other causes.
Humidity and cooling by zone
- Humid zones (1, 2A, 3A, 4A): turn on the thermostat’s dehumidify or “overcool to dehumidify” setting if it has one, and use fan Auto rather than On in summer. A fan left running blows moisture off the cold coil back into the house. Keep indoor humidity under about 60%.
- Dry zones (2B, 3B, 4B, 5B): cooling works well at a higher setpoint because dry air feels cooler, and indoor air can get very dry in winter. If you have a whole-house humidifier, wire and set it up through the thermostat’s accessory terminals, aiming for about 30–40% in winter and lower when it’s very cold outside to avoid condensation on windows.
- Marine zones (3C, 4C): mild all year, so heat pumps rarely need aux heat. Many homes need little or no cooling.
- Cold zones (6–8): make sure the thermostat’s minimum setpoint or “away” temperature never lets the house fall far enough to freeze pipes, about 55 °F at the lowest when you’re away in winter.
Check your wiring first
Lockout and humidity settings only show up when the thermostat knows what it controls. If the app doesn’t offer them, the equipment setup is probably wrong: see settings to check after installing, or tick your old terminals in the wiring tool to confirm whether you have a heat pump, aux heat or a dual-fuel system.