G-Shock GW-9200BPJ-1 - Manual (Page 83)

E-81
Questions & Answers
Question: How does the barometer work?
Answer: Barometric pressure indicates changes in the atmosphere, and by
monitoring these changes you can predict the weather with
reasonable accuracy. Rising atmospheric pressure indicates good
weather, while falling pressure indicates deteriorating weather
conditions.
The barometric pressures that you see in the newspaper and on the
TV weather report are measurements corrected to values measured
at 0 m sea level.