Most homes need less dehumidifying in winter, but you may still need one
Winter air is naturally drier because cold air holds less moisture than warm air. When you heat your home, the air becomes even drier — heating lowers relative humidity without adding moisture. For most people in most climates, running a dehumidifier in winter wastes energy and money. However, if your home stays damp despite the season, or if you live in a humid coastal or subtropical climate, winter dehumidifying may still make sense.
The real question is not whether it is winter, but whether your indoor humidity is actually high. A hygrometer — a cheap tool that measures humidity — tells you what you are actually dealing with. Ideal indoor humidity sits between 30 and 50 percent. If your reading is above 50 percent in winter, investigate the source before running a dehumidifier.
Key Takeaways
- Winter air is naturally dry, so most homes do not need dehumidifying from November through March unless they have a specific moisture problem.
- A hygrometer costs $10 to $30 and tells you whether your humidity is actually high enough to warrant a dehumidifier.
- Common winter moisture sources include unvented bathrooms, wet basements, drying laundry indoors, and poor ventilation in kitchens.
- Running a dehumidifier in winter costs more in heating energy than it saves in dehumidifying, because the unit generates heat that your furnace then works to cool.
- Coastal and subtropical regions may need winter dehumidifying year-round, but most inland areas do not.
Why winter humidity happens in the first place
High humidity in winter usually comes from a specific source, not from outdoor air. Unvented or poorly vented bathrooms are the most common culprit — a 20-minute shower adds a gallon of water to your home's air. If that moisture has nowhere to go, it stays in the walls and air. Kitchens without range hoods, wet basements, or drying laundry indoors create the same problem.
Some homes have structural issues: foundation cracks that let groundwater seep in, or crawl spaces that stay damp year-round. These problems do not go away in winter. If your basement or crawl space is wet, a dehumidifier may help manage the symptom, but it does not fix the leak. You will run the dehumidifier constantly and still not solve the underlying issue.
Coastal homes and homes in subtropical regions like parts of Florida, Louisiana, and southern California stay humid even in winter. The outdoor air itself is moist, so heating it does not dry it out as much as it does inland. If you live in one of these areas, your winter humidity patterns may look more like a humid summer elsewhere.
The energy cost of winter dehumidifying
A dehumidifier removes moisture by running a compressor and fan, which generates heat as a byproduct. In winter, your furnace then has to work harder to maintain your target temperature, because the dehumidifier is adding unwanted heat to a space you are already paying to heat. You end up paying twice: once to run the dehumidifier, and again to cool down the extra heat it produces.
The math is straightforward. A typical dehumidifier uses 300 to 700 watts depending on size and model. Running it eight hours a day for three months costs $20 to $50 in electricity. But your furnace has to offset that heat, which can easily cost another $30 to $80 in heating fuel over the same period. The total cost of winter dehumidifying often exceeds $50 to $130 for a season, with no benefit if the humidity problem is not actually there.
In summer, a dehumidifier actually saves money because it reduces the load on your air conditioner. In winter, it adds to your heating bill. This is why most manufacturers and energy guides recommend turning off dehumidifiers from late fall through early spring.
When you should still run one in winter
If your hygrometer reads above 55 percent consistently, or if you have visible mold, condensation on windows, or a musty smell, a dehumidifier may be worth running despite the season. Mold grows above 60 percent humidity and can damage wood framing and create health problems. If you are in that territory, the cost of the dehumidifier is cheaper than mold remediation.
Homes with wet basements or crawl spaces often need year-round dehumidifying. If water is actively seeping in, you have a structural problem that dehumidifying alone will not solve, but it can prevent mold while you arrange repairs. Run the dehumidifier in the affected area only — a basement dehumidifier does not need to run upstairs — to keep costs down.
If you live in a coastal or subtropical climate where outdoor humidity stays high even in winter, you may need to run a dehumidifier year-round. Check your local climate data: if your area averages above 60 percent outdoor humidity in January, winter dehumidifying is normal for your region.
Fixing the source instead of treating the symptom
Before you buy or run a dehumidifier, fix what is causing the moisture. Install or repair exhaust fans in bathrooms and kitchens so moisture leaves the house instead of staying in it. Make sure fans vent outside, not into an attic or crawl space. Run the bathroom fan during and for 20 minutes after a shower.
Dry laundry outdoors or in a vented dryer, not on racks inside your home. If you must dry clothes indoors, run a window fan or exhaust fan to push the moisture out. Seal foundation cracks and install a sump pump or drainage system if water is entering your basement. These fixes cost more upfront but eliminate the need for constant dehumidifying.
Improve ventilation by opening windows on dry days, even in winter. A few minutes of fresh air exchange can drop indoor humidity significantly. In very cold climates this is not practical, but in milder winters it works well.
Choosing a dehumidifier if you do need one in winter
If you have confirmed that your winter humidity is genuinely high and you have ruled out straightforward fixes, choose a dehumidifier sized for the space where the moisture problem occurs. A basement dehumidifier does not need to be large enough for your whole house. Smaller units use less energy and are easier to maintain.
Look for a model with an automatic shutoff when the tank is full, or better yet, a continuous drain option so you do not have to empty it by hand. Some dehumidifiers have a frost sensor that shuts the unit off if the coils get too cold — this is useful in winter because cold air reduces dehumidifier efficiency anyway.
Run the dehumidifier only in the room or area where humidity is actually high. Close doors to other rooms. Check your hygrometer weekly to see whether the unit is actually bringing humidity down. If it is not, the problem is likely structural and dehumidifying alone will not solve it.
Frequently Asked Questions
Will running a dehumidifier in winter make my heating bill go up?
Yes. A dehumidifier generates heat as it runs, so your furnace has to work harder to maintain your target temperature. The combined cost of running both usually exceeds the benefit, unless your humidity is dangerously high or you live in a naturally humid climate.
What humidity level is too high in winter?
Above 55 percent is worth investigating. Above 60 percent creates conditions where mold can grow. If your hygrometer reads above 60 percent and you see condensation on windows or smell mustiness, run a dehumidifier until humidity drops to 45 to 50 percent, then address the source of the moisture.
Can I just close off rooms and run a dehumidifier in one area?
Yes, and this is the most cost-effective approach. A small dehumidifier in a basement or bathroom uses far less energy than a large unit trying to dry your whole house. Close doors to other rooms and run the unit only where the moisture problem actually exists.
Should I turn off my dehumidifier in winter?
If your humidity stays below 50 percent without it, yes — turn it off and save the energy cost. If humidity climbs above 55 percent even in winter, keep it running. Use a hygrometer to track humidity week to week so you know when to switch it on and off.
What if my dehumidifier is not lowering humidity in winter?
Dehumidifiers work less efficiently in cold air, and they cannot overcome a major moisture source like an active leak. If humidity is not dropping after a week of running, the problem is likely structural. Stop running the unit and focus on finding and fixing the source — a wet basement, unvented bathroom, or poor ventilation.