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indoor air, naturally.

dewdrop is an indoor humidity and natural ventilation app. It compares the absolute humidity inside your home with outdoor weather conditions, helping you decide when opening the windows can remove moisture and replace stale indoor air.

Yes. dewdrop requires no account, contains no ads or tracking, and keeps sensor data and your location data on your devices and within Apple services.

dewdrop is especially useful in homes without central heating or cooling, where opening windows is an essential way to manage indoor humidity. Everyone can benefit from regular Lüften: briefly opening windows to replace stale, humid indoor air with fresher, usually drier air when outdoor conditions are suitable.

Sustained relative humidity above 60% can encourage condensation and create conditions where mold may grow, potentially damaging walls, furniture, artwork, and other belongings. Damp or moldy environments may also cause symptoms in some people, particularly those with asthma or mold sensitivities. dewdrop helps you monitor humidity and identify opportunities to reduce moisture naturally, but it does not detect or remediate mold.

Yes. Plants, guitars and other musical instruments, cigars, wine, wooden furniture, artwork, books, and other moisture-sensitive belongings can require particular humidity conditions. dewdrop lets you set custom targets and alerts, then shows whether outdoor air may help move a room toward the desired range.

Outdoor air is often drier than the air inside, opening the windows allows indoor moisture to escape. dewdrop shows the best natural ventilation timing.

dewdrop compares indoor temperature and humidity (entered manually or provided by supported HomeKit sensors) with current outdoor weather and forecast data. It utilizes absolute humidity in its calculations to show when opening the windows is likely to remove moisture.

No. You can manually enter your indoor temperature and humidity in dewdrop. If you already use supported HomeKit sensors, dewdrop can also use their readings for room-by-room guidance.

Yes. dewdrop provides room-by-room humidity guidance and customizable alerts. Notifications can appear immediately or only after a humidity condition has persisted.

dewdrop may help you use naturally drier outdoor air before turning to a dehumidifier, heating, or air conditioning. It also warns when outdoor temperatures could make ventilation increase your heating or cooling costs.

Outdoor air may be dry enough to reduce indoor humidity but still be uncomfortably hot or cold. dewdrop warns about temperature extremes so you can weigh the moisture benefit against the energy needed to heat or cool the incoming air.

When a room is much colder than room temperature, you should heat the room instead of opening a window to get humidity under control.

Yes, but use caution. dewdrop has this warning not because rainy air is always more humid than your indoor air (usually it is not) but to avoid getting water in your window tracks to prevent mold growth.

Relative humidity changes with temperature. Two air masses can have the same relative humidity while containing different amounts of water vapor. dewdrop uses absolute humidity to determine whether outdoor air can actually remove moisture from your home.