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What months should you use a dehumidifier?

Humidity levels tend to fluctuate based on the season and weather patterns. Knowing when humidity is highest can help determine the optimal times to use a dehumidifier. Generally, a dehumidifier is most useful during the warmer summer months when humidity levels spike. However, depending on your climate and living conditions, you may find using a dehumidifier is beneficial year-round.

What is considered high humidity?

Normal humidity levels range between 30-50% relative humidity. Humidity levels above 50% are considered high and can cause discomfort, mold growth, musty smells, and damage to your home and possessions. The highest humidity levels occur when the air temperature and moisture content are high.

What months are most humid?

The most humid months are generally during the summer. However, this can vary by region. Below are some guidelines for the most humid months by region:

  • Northeast US – July and August
  • Southeast US – July through September
  • Midwest US – July and August
  • Southwest US – August and September during monsoon season
  • Western US – Varies by state, highest humidity along the coast
  • Northern Europe – July through September
  • Southern Europe – July and August
  • Tropics – Year-round high humidity, rainy seasons spike humidity further

Within the humid months, the most humid days tend to be when a heat wave occurs. The combination of high temperatures and stagnant air causes humidity levels to soar. Track weather forecasts in your area to identify upcoming hot, humid periods.

Ideal humidity levels by month

Here are the ideal humidity levels to aim for each month:

Month Ideal Humidity Level
January 30-40%
February 30-40%
March 30-50%
April 30-50%
May 30-50%
June 30-50%
July 30-50%
August 30-50%
September 30-50%
October 30-50%
November 30-40%
December 30-40%

As you can see, the ideal humidity range creeps higher during the spring and summer months when hotter temperatures drive up moisture levels. The lower humidity recommendations during winter are to deter mold growth and condensation issues.

Benefits of using a dehumidifier

There are many benefits to using a dehumidifier when humidity levels are high:

Improves comfort

High humidity causes the air to feel muggy and oppressive. Running a dehumidifier can remove that moisture from the air, making indoor spaces feel fresher.

Reduces allergies & asthma symptoms

High humidity promotes the growth of mold, mildew, dust mites, and other allergens. Dehumidifying the air can help keep allergens under control.

Protects your home & possessions

Excess moisture can damage your home and belongings. It can peel paint, warp floors and furniture, promote mold growth, and cause metals to corrode. Dehumidifying protects your investment.

Eliminates musty odors

That damp, mildewy smell is never pleasant. Dehumidifiers remove the excess moisture that causes musty odors in basements, closets, and other areas.

Makes laundry dry faster

Trying to dry laundry in high humidity is frustrating. Dehumidified air allows laundry to dry faster without getting stiff and mildewy.

Improves health

Humidity provides the perfect breeding ground for bacteria, viruses, and dust mites that can aggravate allergies and illnesses. Dehumidifiers allow you to breathe healthier air.

Tips for getting the most from your dehumidifier

Follow these tips to use your dehumidifier most effectively:

  • Place it in the dampest room in your home, keeping interior doors open to help circulate air.
  • For whole-home dehumidification, place units in problem areas like the basement.
  • Empty the water reservoir frequently so the unit doesn’t overflow.
  • Clean the filter monthly to remove dust and keep airflow optimal.
  • Use a hygrometer to monitor humidity levels and adjust the dehumidifier as needed.
  • Pair it with an air conditioner to remove heat and humidity.
  • Have your HVAC system serviced to ensure condensation pans drain properly.
  • Run the unit continuously rather than only when humidity spikes.
  • Use exhaust fans when showering or cooking to remove excess moisture.
  • Fix water leaks to eliminate a major source of humidity.
  • Make dehumidification a priority if anyone in your home has asthma or allergies.

Signs you need a dehumidifier

Watch for these signs that indicate your home’s humidity levels may be too high:

  • Mildew, mold or musty smells
  • Damp spots on walls and ceilings
  • Curling wallpaper or ceiling tiles
  • Sweating windows and pipes
  • Peeling paint
  • Condensation on windows
  • Damp, clammy feeling indoors
  • Floors feel sticky or tacky
  • Wood furniture has expanded in size
  • Laundry takes a long time to air dry
  • You or family members have respiratory issues

Any of these issues indicate you need more dehumidification in your home.

Types of dehumidifiers

There are several types of dehumidifiers to consider:

Refrigerant dehumidifiers

These are the most common and use a refrigeration system with coils to condense and collect water from the air. They are ideal for medium to large rooms.

Desiccant dehumidifiers

They use a desiccant material like silica gel to absorb moisture, then heat the material to remove the moisture it collected. They work better in colder temperatures.

Whole-house/ducted dehumidifiers

As the name implies, these are installed with a home’s ductwork to dehumidify the whole house. Helpful for very damp climates.

Mini dehumidifiers

Compact electric units that work best in small rooms up to 1500 sq ft. Easy to move room to room.

Heat pump dehumidifiers

Work similarly to refrigerant models but are more energy efficient. Pricier upfront but lower operating costs.

Desiccant wheel dehumidifiers

Contain a large desiccant coated wheel that rotates to absorb then discharge moisture. Very effective but more expensive.

Sizing dehumidifier capacity

Choosing a dehumidifier with the right moisture removal capacity is key. To determine the appropriate capacity:

  • Calculate the room’s square footage where the unit will be used.
  • Look at the humidity level you want to maintain, such as 45-50%.
  • Check the dehumidifier’s pint capacity and match it to room size and humidity needs.
  • Allow for extra capacity if the space is exceptionally damp.
  • Prioritize higher moisture removal for large spaces like basements.

A good minimum capacity is 15-20 pints per day for a 500 sq ft room. Increase capacity to 30-45 pints for larger, damper spaces. Units are available in capacities up to 90 pints for very wet areas.

Dehumidifier pros & cons

Dehumidifiers have advantages and disadvantages to weigh:


  • Improve indoor air quality
  • Help control allergies/asthma
  • Prevent mold and mildew growth
  • Protect home from moisture damage
  • Reduce musty odors
  • Allow damp items to dry faster


  • Purchase cost
  • Ongoing energy costs
  • Noise from unit operation
  • Requires emptying water tank
  • Need proper placement and capacity

Many find the pros far outweigh the cons when it comes to enjoying lower humidity and healthier indoor air.

Operating costs

Dehumidifier operating costs depend on:

  • Unit size – Larger capacity equals more energy use
  • Usage time – Running it 24/7 uses more energy than intermittent use
  • Electricity rate – Cost per kilowatt hour affects overall costs
  • Features – Auto shutoff and timers reduce energy use
  • Age of unit – Older models may be less energy efficient
  • Supplemental drying – Using fans/AC to assist drying lowers run time
  • Home construction – Tighter, better insulated homes stay drier
  • Climate conditions – Cooler, drier climates require less run time

A medium-capacity dehumidifier running six hours per day can cost $40-$60 per month to operate. Bigger units running constantly can cost over $100 per month. Newer Energy Star rated models are your most cost-effective options.


Regular dehumidifier maintenance includes:

  • Cleaning air filter monthly
  • Wiping down exterior to remove dust/grime
  • Emptying water tank promptly when full
  • Checking coils yearly for dust/debris
  • Vacuuming condenser coils if needed
  • Ensuring unobstructed air flow to and from unit
  • Checking condensate hose for obstructions
  • Listening for abnormal noises indicating an issue
  • Checking power cord and outlet condition
  • Monitoring run time hours and replacing filter per manual

This basic care will keep any dehumidifier operating efficiently for many years.


Humidity levels fluctuate through the year with warmer months typically needing more dehumidification. However, damp basements, crawlspaces and construction issues can cause a need for dehumidification year round in some homes. Pay attention to signs of high humidity and musty odors to determine when you should be running a dehumidifier. Portable units allow you to use dehumidification only where and when you need it most to save energy costs while maintaining healthier indoor humidity levels.