Running a dehumidifier in winter depends on your indoor humidity level, not the season
You should run a dehumidifier in winter only if your home's indoor humidity stays above 50 percent. Winter air is naturally dry, so most homes do not need one during cold months. However, certain situations—a basement that stays damp, a bathroom with poor ventilation, or a home heated with a humidifier—can trap moisture indoors even when outdoor air is frozen. The goal is to keep humidity between 30 and 50 percent year-round, which protects both your home and your health.
Before you plug in a dehumidifier, measure your actual humidity with an inexpensive hygrometer (a small meter that costs $10 to $30). This tells you whether you have a moisture problem or whether the air is already dry enough. Running a dehumidifier when humidity is already low wastes electricity and can make the air uncomfortably dry, causing dry skin, static shock, and respiratory irritation.
Key Takeaways
- Winter humidity above 50 percent is the only reason to run a dehumidifier; outdoor cold naturally dries indoor air, so most homes do not need one in winter.
- A hygrometer costs $10 to $30 and tells you your actual humidity level—measure before deciding to run a dehumidifier.
- Basements, bathrooms, and homes with humidifiers can trap moisture in winter and may need a dehumidifier even when it is cold outside.
- Running a dehumidifier in already-dry winter air wastes electricity and can cause dry skin, static, and respiratory discomfort.
- If you do run a dehumidifier in winter, empty the tank or drain it regularly because cold air holds less moisture and the unit may not cycle off as often.
Why winter air is naturally dry
Cold air holds much less moisture than warm air. When outdoor temperature drops, the air's ability to hold water vapor drops sharply—at 32°F, air can hold only about one-third the moisture it holds at 70°F. This is why winter air feels dry on your skin and lips, and why static electricity becomes a problem.
When you heat that cold outdoor air inside your home, it becomes even drier. If outdoor air is 20°F and 40 percent humid, and you heat it to 70°F indoors without adding moisture, the relative humidity inside drops to roughly 10 to 15 percent. This is why most homes naturally dry out in winter without any help from a dehumidifier. Adding a dehumidifier to this already-dry environment removes moisture you may actually need.
When winter humidity stays high enough to need a dehumidifier
Basements are the most common place where winter humidity stays elevated. Concrete walls and floors absorb groundwater year-round, and cold outdoor air does not prevent this seepage. If your basement humidity reads above 50 percent on a hygrometer, a dehumidifier can help prevent mold, musty odors, and damage to stored items.
Bathrooms with poor ventilation also trap moisture in winter. If you shower and the exhaust fan is missing, blocked, or vents into the attic instead of outside, humidity can linger in the bathroom and spread to nearby rooms. Running a dehumidifier in the bathroom or hallway can help, but fixing the exhaust vent is the permanent solution.
Homes that use a humidifier to combat dry winter air can end up with too much moisture if the humidifier is set too high or if it runs constantly. If you use a humidifier and your windows fog up, or if you see condensation on cold walls or windows, your indoor humidity is too high. In this case, lower the humidifier setting first—do not add a dehumidifier without measuring humidity first.
How to measure humidity before you decide
A hygrometer is a small battery-powered meter that displays the current humidity percentage in your home. Digital models are most accurate and cost $15 to $30. Place it in the room where you suspect moisture problems—usually a basement, bathroom, or bedroom—and let it sit for 10 to 15 minutes to stabilize.
Take readings at different times of day and on different days. Humidity changes with temperature, time of day, and how much moisture-producing activity (cooking, showering, laundry) happens in your home. If readings consistently stay above 50 percent, a dehumidifier may help. If they stay below 40 percent, the air is already dry and a dehumidifier will only make it drier.
Electricity cost and efficiency in winter
Dehumidifiers use more electricity in winter than many people expect because they run longer. In summer, warm air holds moisture, so a dehumidifier removes water quickly and cycles off. In winter, cold air holds less moisture, so the dehumidifier has to run longer to pull the same amount of water out of the air. A typical portable dehumidifier uses 300 to 700 watts, which costs roughly $0.04 to $0.08 per hour to run, depending on your local electricity rate.
If you run a dehumidifier 8 hours a day for 3 winter months, the electricity cost is roughly $30 to $60 for that period. This is worth it if you have a genuine moisture problem—mold damage or water intrusion costs far more. But if humidity is already low, that cost is pure waste.
Maintenance and tank management in winter
If you do run a dehumidifier in winter, check the collection tank or drain line more often than you would in summer. Cold air holds less moisture, so the unit removes water more slowly and the tank fills more gradually. However, if the room is particularly damp or if the dehumidifier is sized too large for the space, it can still fill quickly.
Most portable dehumidifiers have a float switch that shuts off the unit when the tank is full, preventing overflow. Empty the tank when it reaches the fill line, or attach a drain hose to a floor drain or sump pump if your dehumidifier has a drain port. If you leave a full tank sitting, water can spill and create the moisture problem you were trying to solve.
Alternatives to running a dehumidifier in winter
Before you buy or run a dehumidifier, address the source of moisture. In a basement, seal cracks in the foundation, install a sump pump if water pools, and run a perimeter drain if the problem is severe. In a bathroom, repair or install an exhaust fan that vents outside (not into the attic). In a kitchen, run the range hood while cooking. These fixes cost more upfront but solve the problem permanently.
If humidity is slightly elevated but not severe, open windows on dry days to let cold outdoor air exchange with indoor air. This is free and works well on days when outdoor humidity is low. Avoid running a humidifier in winter unless your hygrometer reads below 30 percent and you have dry skin or respiratory symptoms—most homes do not need one.
Frequently Asked Questions
Will running a dehumidifier in winter damage my home?
No, but running one in already-dry air wastes electricity and can make indoor air uncomfortably dry. If humidity is below 30 percent, the air is already too dry and a dehumidifier will make it worse. Check your humidity with a hygrometer before deciding to run one.
Can a dehumidifier freeze in winter?
Yes, if the room temperature drops below 60°F, the moisture the dehumidifier pulls from the air can freeze on the cooling coils, blocking airflow and reducing performance. Most dehumidifiers are designed for indoor use in heated spaces. If your basement is unheated, a dehumidifier may not work well in deep winter.
Should I run a dehumidifier if my windows fog up in winter?
Yes, window condensation means indoor humidity is too high. Measure with a hygrometer first—if humidity is above 50 percent, a dehumidifier can help. But also lower the setting on any humidifier you are running, and make sure bathroom and kitchen exhaust fans vent outside, not into the attic.
How long should I run a dehumidifier in winter?
Run it only as long as needed to keep humidity between 30 and 50 percent. If you run it continuously and humidity drops below 30 percent, turn it off. Many dehumidifiers have a built-in humidistat that automatically cycles the unit on and off based on a humidity target you set.
Is it cheaper to run a dehumidifier or a humidifier in winter?
Both use similar amounts of electricity (roughly $0.04 to $0.08 per hour). The real cost is whether you need one. Most homes do not need either in winter—outdoor air is naturally dry, and heating it indoors dries it further. Measure humidity before buying either appliance.