When reading the pressure sensor on your Wave Plus or View Plus, you will often notice there is a difference in the pressure you see, against what you see for example on weather.com or yr.no 

The explanation for this is quite simple! The reason for the difference is because the measurement that is provided from these sources are based at sea-level. This provides a baseline measurement to work from that can be adjusted based on your elevation. The higher the elevation where you live, the lower the air-pressure will be. Additionally, temperature and indoor mechanical ventilation can also play a role in your indoor air pressure levels. 

Here is a helpful calculator that you can use to understand the change in air pressure with elevation: https://www.omnicalculator.com/physics/air-pressure-at-altitude