I tried yesterday, using WeeWX v.3.9.2, to calibrate my WH1080 barometer by adding
pressure = pressure - 2.9
under
[StdCalibrate]
[[Corrections]]
in weewx.conf. The result, shown in the image below, is not what I expected -- a drop of almost 100 mbar. The spike is because I rescinded the edit. Is this a bug or have I missed something?