For stand-alone weather stations, the barometric pressure is detected and registered internally within your weather station. It can take up to 3 weeks to fully acclimate to your atmospheric changes and register properly.
If you live at an elevation of 5000 ft, the barometric pressure may start reading inaccurately. If you live at an elevation of 6000 ft, or above, the barometric pressure on the unit will not work. These units are not sensitive enough to detect the smaller barometric pressure changes at higher altitudes.