Inverse Barometer Effect
This is taken at seal level Nick, and is an average globally, but yes you are correct. Certain regions would have a higher or lower averages than this.
Ah I just mentioned that to clarify we're talking Mean Sea Level Pressure (MSLP).
If higher in altitude like up a mountain the pressure is lower, but the ocean doesn't go higher than sea level :p
Hmm, not off the top of my head, you'd have to search for the long term climate data for that info.
In reagrds too the subject title, if i recall correctly, the average air pressure was 1013, anything higher or lower would have an effect on the tide prediction.
If so, would that 1013 be nation wife, surely each region would have different averages?