Heat pumps work in cold climates, but their efficiency drops as outdoor temperature falls

Heat pumps pull warmth from outside air or ground and move it indoors. In mild climates—where winter lows stay above 30°F—they run at peak efficiency and can heat a home for less money than a furnace. In cold climates where temperatures regularly drop below 0°F, a heat pump still works, but it has to work harder. The colder the air outside, the less heat there is to extract, so the system runs longer and uses more electricity to reach your target indoor temperature.

This does not mean heat pumps fail in cold weather. Modern cold-climate heat pumps are engineered to operate down to –13°F or lower. What changes is the math: your heating bills may be higher than they would be with a gas furnace, or you may need a backup heating source to keep costs down. The best climate for a heat pump is one where winter temperatures rarely dip below freezing, but that does not rule out colder regions—it just changes what you should expect to pay.

Key Takeaways

  • Heat pumps reach their highest efficiency in climates where winter lows stay above 30°F, such as the Pacific Northwest, parts of the Northeast, and the Southeast.
  • In climates where temperatures regularly fall below 0°F, a heat pump still heats your home but draws more electricity and may cost more to run than a gas furnace.
  • Modern cold-climate heat pumps can operate at outdoor temperatures as low as –13°F, though efficiency drops significantly below 20°F.
  • Homes in very cold climates often pair a heat pump with a backup heating system—usually electric resistance heat or a gas furnace—to manage costs during extreme cold snaps.
  • Ground-source heat pumps maintain steadier efficiency across all climates because soil temperature stays more stable than air temperature, but they cost more to install.

Mild climates where heat pumps work most efficiently

Heat pumps perform best in regions where winter temperatures rarely drop below freezing and summer cooling is moderate to heavy. The Pacific Northwest (western Washington, Oregon, and northern California) is ideal: winters are wet and mild, and the region rarely sees sustained freezes. The Southeast—including parts of Georgia, the Carolinas, and Tennessee—also suits heat pumps well because heating seasons are short and cooling demand is high. Parts of the Mid-Atlantic, such as Virginia and Maryland, fall into this range too.

In these climates, a heat pump can be your only heating and cooling system. It runs efficiently year-round, and your heating bills are typically lower than they would be with a gas furnace because the heat pump moves existing warmth rather than burning fuel to create it. You do not need a backup system, and maintenance is straightforward: annual service for the outdoor unit and filter changes indoors.

Cold climates where heat pumps need a backup system

In climates where winter lows regularly fall below 0°F—such as Minnesota, Wisconsin, upstate New York, and parts of New England—a heat pump still heats your home, but efficiency drops sharply. Below 20°F, the outdoor air holds so little heat that the heat pump's compressor works continuously and may cycle on and off more often. At –13°F and below, many heat pumps automatically switch to electric resistance heating (a backup element inside the unit) because pulling heat from the air becomes too expensive.

Homeowners in these regions typically install a heat pump paired with a backup heating source. The heat pump handles most of the heating season when temperatures are above 20°F or so. When a cold snap arrives, the backup system—usually electric resistance heat built into the heat pump, or a gas furnace—takes over. This setup costs more upfront than a furnace alone, but it can still save money if your electricity rates are low and you have good insulation, because the heat pump runs efficiently for much of the year.

Very cold climates and extreme-weather considerations

In regions where temperatures drop below –13°F for extended periods—parts of Alaska, northern Minnesota, and the Upper Peninsula of Michigan—a standard air-source heat pump becomes impractical as a primary heating system. The outdoor unit must work so hard that electricity consumption spikes, and many homeowners find that a gas furnace or oil furnace is cheaper to operate. Some cold-climate heat pumps are rated to –22°F, but even these lose efficiency rapidly below –13°F.

If you live in an extreme-cold region and want a heat pump, a ground-source heat pump (also called a geothermal heat pump) is a better choice. Ground temperature stays around 50°F year-round, even when air temperature plummets. A ground-source heat pump pulls heat from the earth through underground loops and maintains steady efficiency regardless of outdoor air temperature. The trade-off is cost: installation runs $15,000 to $30,000 or more because it requires digging or drilling, whereas an air-source heat pump costs $5,000 to $15,000 installed. But in very cold climates, the efficiency gain can justify the higher upfront expense over time.

How humidity and precipitation affect heat pump performance

Humidity and rain do not stop a heat pump from working, but they do affect how it operates. In humid climates—the Southeast, Gulf Coast, and parts of the Midwest—heat pumps excel at cooling because they remove moisture as they cool. In dry climates like the Southwest, a heat pump still cools, but you may notice less dehumidification benefit.

Rain and snow do not damage an outdoor heat pump unit, but heavy snow accumulation can block airflow around the unit, reducing efficiency. If you live in a region with frequent heavy snow, you may need to clear snow away from the outdoor unit during winter storms. Frost buildup is another consideration: when outdoor temperature hovers near freezing and humidity is high, frost can coat the outdoor coil. Modern heat pumps have a defrost cycle that melts this frost automatically, but the cycle uses energy and temporarily reduces heating output.

Comparing air-source and ground-source heat pumps by climate

An air-source heat pump is the standard choice for most climates because it costs less to install and works well where winter temperatures stay above 0°F. It is the right fit for the Pacific Northwest, Southeast, and much of the Mid-Atlantic. A ground-source heat pump makes sense if you live in a very cold climate, have space for underground loops, and plan to stay in your home long enough to recoup the higher installation cost—typically 10 to 15 years or more.

There is also a middle ground: a cold-climate air-source heat pump, which is engineered to maintain efficiency down to –13°F or lower. These units cost slightly more than standard air-source heat pumps but less than ground-source systems. They are a good choice for the upper Midwest and Northeast if you want to minimize backup heating use without the expense of a ground-source system.

What to consider when choosing a heat pump for your climate

Before buying a heat pump, know your region's average winter low temperature and how many days per year it falls below 0°F. Your local utility company or a heating contractor can tell you this. If winter lows rarely drop below 30°F, a standard air-source heat pump is your best option. If lows regularly fall between 0°F and 20°F, consider a cold-climate air-source heat pump or a standard model paired with a backup furnace. If lows frequently drop below –13°F, a ground-source heat pump or a very cold-climate air-source model with backup heat is more practical.

Also consider your home's insulation and air sealing. A well-insulated, airtight home needs less heating and cooling, which makes a heat pump more efficient and cost-effective regardless of climate. If your home has poor insulation or air leaks, a heat pump will work, but you will not see the full efficiency benefit. Addressing insulation and air sealing before installing a heat pump often pays off faster than the heat pump itself.

Frequently Asked Questions

Can I use a heat pump if I live where it gets below zero?

Yes. Modern heat pumps operate at temperatures below zero, though efficiency drops significantly. Most homeowners in cold climates pair a heat pump with a backup heating system—either electric resistance heat or a gas furnace—so the backup takes over during extreme cold and keeps electricity costs manageable.

What temperature is too cold for a heat pump?

Standard air-source heat pumps lose efficiency below 20°F and become impractical below –13°F. Cold-climate heat pumps are rated to operate at –13°F or lower, but efficiency still drops. Below –22°F, even cold-climate models struggle, and a ground-source heat pump or traditional furnace is usually more practical.

Do heat pumps work in humid climates?

Yes, and they work very well. Heat pumps remove humidity while cooling, which is especially valuable in humid regions like the Southeast and Gulf Coast. They also heat efficiently in humid climates as long as winter temperatures stay above freezing most of the time.

Is a ground-source heat pump worth the cost in a cold climate?

A ground-source heat pump costs $15,000 to $30,000 or more to install, compared to $5,000 to $15,000 for an air-source model. In very cold climates where an air-source heat pump would need frequent backup heating, a ground-source system can save enough on heating bills over 10 to 15 years to justify the higher upfront cost. A heating contractor can estimate your payback period based on your home and local energy rates.

Will snow or ice damage my outdoor heat pump unit?

No. Heat pump units are built to withstand snow and ice. Heavy snow can block airflow around the unit, so clear it away if accumulation is deep. Frost buildup on the coil is normal and the unit's defrost cycle handles it automatically, though this uses some energy temporarily.