Winter humidifier setting
In winter, the colder it is outside, the lower you must set indoor humidity or your windows will stream with condensation. Enter the outdoor temperature for the recommended maximum setting.
Evidence-checked. Facts and figures on this page are verified against published standards and government sources (Window-industry cold-weather humidity guideline (double-pane)). Last verified July 2026 — our methodology.
Recommended indoor humidity
—
- Outdoor temp
- —
- Window type
- Double-pane
- Comfort floor
- Keep above 30%
This is the long-standing window-industry guideline for double-pane glass: as the outdoor temperature falls, the inside of the window gets colder, so the indoor humidity that would fog or frost it drops too. Single-pane or drafty windows need lower settings; efficient triple-pane or storm windows tolerate a little more. If your glass still sweats at this level, drop another 5%.
Why winter humidity has a ceiling
Heating dry winter air makes homes feel parched, so a humidifier helps — but every window is a cold surface waiting to collect that added moisture. The colder it is outside, the lower the indoor humidity has to stay to keep the glass clear. Aim to stay between about 30% (for comfort) and the ceiling this tool gives. To see exactly when a specific window will sweat, use thewindow condensation calculator; to understand the physics, readcondensation on the inside of windows. For the healthy year-round band, seeideal indoor humidity levels.