A dehumidifier will not cool your room, but it may feel cooler
A dehumidifier removes moisture from the air, not heat. The machine pulls humid air across cold coils, water condenses and drains away, and the dried air returns to the room at roughly the same temperature it entered — or slightly warmer, because the motor generates heat. If your room is 78°F and 70% humidity, a dehumidifier will lower the humidity to 50% but leave the temperature at 78°F or push it to 79°F.
However, you may feel cooler. Humid air prevents sweat from evaporating off your skin, so your body cannot shed heat efficiently. When humidity drops, sweat evaporates faster and you feel more comfortable — even though the actual air temperature has not changed. This is why 78°F at 30% humidity feels more bearable than 78°F at 70% humidity. The sensation of coolness is real, but the room itself is not cooler.
If you need to lower the actual temperature, you need air conditioning or a fan. A dehumidifier is useful for comfort and to prevent mold and mildew, but it is not a cooling tool.
Key Takeaways
- A dehumidifier removes water from the air but does not lower room temperature; it may even raise it slightly because the motor produces heat.
- You will feel more comfortable in a dehumidified room because your body can cool itself through sweat evaporation, even though the thermometer reads the same.
- If your goal is to lower room temperature, an air conditioner or fan is necessary; a dehumidifier alone will not do it.
- Dehumidifiers work best in basements, bathrooms, and other damp spaces where moisture is the main problem, not heat.
Why dehumidifiers produce heat instead of cold
A dehumidifier works by running warm air over refrigerated coils. The moisture in the air condenses on those cold coils and drains into a tank or hose. The now-dry air passes over the warm condenser coils on the back of the machine — the part that releases heat — before returning to the room. This cycle means the air leaving the dehumidifier is warmer than the air that entered it.
The amount of heat added is usually small, between 2°F and 5°F, but it is real. A 50-pint dehumidifier running continuously in a sealed room will gradually raise the temperature. This is why dehumidifiers are least efficient in already-warm spaces and most useful in cool, damp basements where that small temperature rise does not matter.
The difference between feeling cooler and being cooler
Comfort depends on both temperature and humidity. Meteorologists call this the "heat index" — the temperature the air feels like when humidity is factored in. At 78°F and 70% humidity, the heat index is around 84°F. At 78°F and 40% humidity, the heat index drops to about 76°F. Your body perceives the second scenario as cooler, even though the thermometer reads 78°F in both cases.
This happens because your skin cools itself by sweating. When humidity is high, sweat cannot evaporate; it sits on your skin and your body temperature rises. When humidity is low, sweat evaporates quickly and your body sheds heat efficiently. A dehumidifier speeds up that evaporation, so you feel relief — but the room temperature itself has not dropped.
When a dehumidifier makes sense for comfort
A dehumidifier is worth running if your space is both humid and already cool enough. Basements, bathrooms after a shower, and laundry rooms are common examples. If your basement stays around 70°F but feels clammy at 65% humidity, a dehumidifier will make it feel more comfortable without requiring you to run an air conditioner.
A dehumidifier is also useful for preventing damage. High humidity causes mold, mildew, wood rot, and rust. If you live in a humid climate or have a damp basement, keeping humidity below 50% protects your home even if the temperature never changes. This is a practical reason to run one, separate from comfort.
In summer, if your room is already too warm, a dehumidifier will not solve the problem. You need air conditioning to lower temperature, or a fan to move air across your skin and speed evaporation. A dehumidifier can run alongside an air conditioner to improve comfort further, but it cannot replace cooling.
Dehumidifier size and room temperature impact
Larger dehumidifiers remove more water but also produce more heat. A 70-pint unit generates more warmth than a 30-pint unit. In a small, sealed room, a large dehumidifier running for hours can noticeably raise the temperature. In a larger space with air circulation, the effect is less noticeable because heat disperses.
If you are concerned about temperature rise, look for a dehumidifier with a low energy rating or one designed for smaller spaces. Some models also have a "continuous drain" option, which uses less energy than models that cycle on and off. Running the dehumidifier during cooler hours — early morning or evening — and opening windows or running a fan can offset any temperature increase.
Alternatives if you need actual cooling
If your room is too warm, a window air conditioner or portable air conditioner will lower the temperature while also removing some humidity. These units are more expensive than dehumidifiers but they solve the actual problem. A window unit typically costs between $150 and $500; a portable unit runs $300 to $800.
A ceiling fan or box fan is much cheaper — $20 to $100 — and will not cool the room but will move air across your skin, making you feel cooler. Fans use far less electricity than air conditioners and work well in combination with a dehumidifier in a humid but not-too-hot space.
If you rent and cannot install a window unit, a portable air conditioner is the next option. It sits on the floor and vents through a window. It costs more than a dehumidifier but actually lowers temperature, which a dehumidifier cannot do.
Frequently Asked Questions
Can I use a dehumidifier instead of air conditioning?
No. A dehumidifier removes moisture but does not lower room temperature. If your room is too warm, you need air conditioning or a fan. A dehumidifier can make a cool, damp room feel more comfortable, but it cannot replace cooling.
Will a dehumidifier help if my room is hot and humid?
It will help you feel more comfortable because lower humidity allows sweat to evaporate, but the actual temperature will not drop and may rise slightly. For real cooling, you need an air conditioner. A dehumidifier works best when the room is already cool enough but too damp.
Does running a dehumidifier raise my electric bill?
Yes, but usually not dramatically. A typical dehumidifier uses 300 to 700 watts, similar to a space heater. Running one continuously for a month might add $10 to $30 to your bill, depending on local electricity rates. An air conditioner uses much more power.
Can I run a dehumidifier and an air conditioner together?
Yes. An air conditioner removes some humidity as it cools, but in very humid climates, a dehumidifier running alongside it can improve comfort further. However, this uses more electricity than either alone, so it makes sense only if humidity remains high even with the air conditioner running.
What humidity level should I aim for?
The EPA recommends keeping indoor humidity between 30% and 50%. Below 30% can cause dry skin and respiratory irritation; above 50% encourages mold and dust mites. A dehumidifier with a built-in humidistat will automatically maintain your target level without you having to monitor it.