Elevation and Barometric Readings: Why Your App Adjusts to Sea Level
Your weather app almost certainly shows sea level pressure, not the actual pressure where you are standing. The two differ by roughly 1 hectopascal for every 8 metres of elevation, which means a barometer in Denver genuinely reads around 840 hPa while the app reports something close to 1015. The adjustment exists so that a weather map can show where the highs and lows actually are, rather than a picture of the terrain. For anyone tracking symptoms against pressure, the adjustment is harmless and arguably helpful, because what the body responds to is change over time, and the adjustment is a near-constant offset that does not affect change.
The confusion this causes is common enough that it is worth walking through properly, especially if you own a home barometer or a weather station that reports something different from your phone.