The humidity level in your home directly affects how comfortable it feels. Too dry and your skin or nasal passages may feel dry; too moist and it may feel clammy indoors. Besides comfort levels, the humidity level is a concern because extremely damp conditions may cause mold or mildew, which can lead to or exacerbate health concerns. Ideal summer and winter indoor humidity vary; in the winter, ideal humidity is in the 25 to 40 percent range; in the summer, less than 60 percent humidity is ideal.
In the winter, air in the home may feel dry, especially if the humidity outdoors is low. If your skin feels itchy and you often are thirsty, the air may be too dry. A digital hygrometer measures indoor humidity. If the humidity is lower than 40 percent, a humidifier adds a bit of moisture to the room.
On a hot, humid day, the air indoors also becomes humid, meaning you may feel uncomfortable or sweaty even indoors. If condensation appears on the inside of windows, this also is an indication of high humidity. An air conditioner or dehumidifier removes excess moisture from the air, making it more dry and comfortable.