Honolulu, Hawaii has the least fluctuation of barometric pressure from 29.34" to 30.32" in mercury. The second is San Diego, California from 29.37" to 30.53" in mercury.
From my understanding, it would be in an area that has a consistent type of weather. An example would be like the desert or the poles where there would be little or no changes in the weather at all.
The barometric pressure least fluctuates in middle of a country as it is inland away from the waters influence. The pressure may fluctuate less in the middle of the ocean.
