Like older aneroid or mercury barometers, our Weather Clocks are made to hang on internal walls. When the atmospheric pressure changes outside, unless you happen to live in a nuclear bunker (!) - or another type of hermetically sealed home - the air pressure will also change to the same extent indoors. So, like your grandfather's barometer he might have tapped everyday in the hallway, you can be happy that your own Weather Clock will pick up the natural changes in atmospheric pressure whilst inside your home.