Indoor humidity in winter is usually best kept in the low-to-mid range so air is comfortable but not damp. Most guidance focuses on a band that protects both your health and your home.
Ideal winter range
For most homes, a relative humidity between about 30% and 40% in winter works well; many sources say 30–50% is acceptable, but the upper end can cause window condensation when it is cold outside. Levels below 30% often feel very dry (static, dry skin, irritated nose and throat), while levels much above 40–45% in cold weather can lead to moisture on windows, walls, and potential mold issues.
Adjusting for outdoor temperature
Recommended humidity also depends on how cold it is outdoors. As outside temperatures drop below freezing, it is safer to keep indoor humidity toward the lower end (around 20–30%) to avoid condensation on cold surfaces; when it is milder (around or above freezing), 30–40% is usually comfortable and safe.
Practical tips
Use a small hygrometer to see what your humidity actually is; adjust humidifiers or dehumidifiers to stay roughly in the 30–40% range in winter and check for window fogging as a warning sign to lower it. If your air feels too dry but windows are staying clear, nudging humidity a bit higher within that range is fine as long as you do not see persistent condensation or musty smells.
