The plot shows the interannual variation of monthly mean sea level and the 5-month running average. The average seasonal cycle and linear sea level trend have been removed. Interannual variation is caused by irregular fluctuations in coastal ocean temperatures, salinities, winds, atmospheric pressures, and ocean currents. The interannual variation for some stations is closely related to the El Niño Southern Oscillation (ENSO).

If present, solid vertical lines indicate times of any major earthquakes in the vicinity of the station or datum shifts and dashed vertical lines bracket any periods of questionable data.