Dry, itchy skin. Static shocks. Wood furniture cracking. Sore throats every morning. If these are winter staples in your Minnesota home, the culprit is almost certainly very low indoor humidity. Understanding why it happens — and what to do about it — makes a real difference in winter comfort and health.
Why Minnesota Winter Air Is So Dry
Cold air holds very little moisture. At -10°F, outdoor air can hold only a tiny fraction of the water vapor that summer air carries. When this cold, dry outdoor air infiltrates your home and gets heated to 70°F, its relative humidity drops dramatically — often to 5–15% RH, which is drier than the Sahara Desert (which averages around 25% RH).
The more air leakage your home has (older homes especially), the more this dry outdoor air replaces indoor air, and the drier your interior becomes. Running a forced-air furnace doesn't create dry air — it just moves the already-dry air around. The furnace isn't the cause, but it doesn't help either without a humidifier.
What Humidity Level Should Your Home Be?
ASHRAE recommends indoor relative humidity of 30–60% for comfort and health. In Minnesota winter, 30–40% RH is a realistic target. Going too high (above 50% in winter) risks condensation on windows and cold exterior walls, which can cause mold and structural moisture damage. The sweet spot for Minnesota winter is 35–45% RH.
A hygrometer (humidity gauge) is an inexpensive tool ($10–$20) that lets you monitor your home's actual humidity. If you don't know what yours is, start there.
Health and Comfort Effects of Low Humidity
Below 30% RH: mucous membranes dry out, which impairs the respiratory tract's natural defense against viruses and bacteria. Research suggests that influenza virus survives and transmits more readily in very dry air (below 20% RH). Dry skin, chapped lips, and itchy eyes are direct physical effects. Wood furniture, hardwood floors, musical instruments, and cabinetry can crack, warp, or separate at joints when exposed to prolonged very low humidity.
Solutions: From Simple to Whole-Home
Portable Humidifiers
An evaporative or ultrasonic portable humidifier can add meaningful humidity to a single room. They're inexpensive ($30–$150), easy to set up, and effective for smaller spaces. Downsides: require daily water refilling, need regular cleaning to prevent mold and mineral buildup, and can't efficiently humidify a whole house in Minnesota's dry climate. Ultrasonic models can deposit white mineral dust on surfaces if used with hard water.
Whole-Home Bypass Humidifier (Evaporative)
Installed on the return air plenum of your forced-air system, a bypass humidifier uses a water panel (evaporator pad) and airflow from the furnace to add moisture to the whole home's air supply. Aprilaire and Honeywell make reliable models in the $150–$300 range. Installation requires cutting into ductwork and connecting to a water supply — about 2–4 hours of work for a competent DIYer or HVAC tech. Bypass models work well for most homes but are less effective in homes with very low natural humidity (very tight, very cold climates) because they rely on furnace operation for moisture dispersal.
Whole-Home Fan-Powered Humidifier
Similar to bypass models but with a built-in fan that runs independently of the furnace blower. More effective in tight, very dry homes because they can add humidity even when the furnace isn't in a heating cycle. Typically $250–$450 in equipment cost. See our whole-home humidifier guide for a full comparison of types and sizing.
Steam Humidifiers
The most powerful whole-home option — generates steam electrically and injects it directly into the air supply. Can maintain 40–50% RH even in the coldest, most air-leaky homes. Equipment cost: $500–$800. Operating cost is higher (uses electricity for steam generation). Aprilaire and Nortec make the most reliable residential steam models.
Addressing the Root Cause: Air Sealing
The fundamental reason Minnesota homes get so dry is air infiltration — cold, dry outdoor air replacing indoor air. Air sealing (weatherstripping, caulking, insulating rim joists, sealing penetrations) reduces this infiltration and makes the home's humidity easier to maintain. Air sealing is one of the highest-ROI home improvement investments in cold climates, reducing both heating costs and humidity loss simultaneously.
Humidity and Your Heating System
Interestingly, maintaining proper indoor humidity makes your home feel warmer at a lower thermostat setting. Humid air at 68°F feels as comfortable as dry air at 72–74°F. Homeowners who add a whole-home humidifier often find they can lower their thermostat 2–3 degrees and maintain the same comfort level — partially offsetting the operating cost of the humidifier with heating savings.
If you're upgrading your furnace, Furnace Direct carries Goodman high-efficiency furnaces at factory-direct wholesale pricing. Browse at furnace.direct/collections/heating.
Related reading: Whole-Home Humidifier Guide | Indoor Air Quality Guide | HVAC Winter Prep Checklist
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