Extreme Water Levels

The monthly extreme water levels include a Mean Sea Level (MSL) trend of 4.53 millimeters/year with a 95% confidence interval of +/- 3.14 millimeters/year which is equivalent to a change of 1.49 feet in 100 years.


Monthly highest and lowest water levels, along with 1%, 10%, 50%, and 99% annual exceedance probability levels shown in red, orange, blue, and purple, respectively. Values are displayed in meters and feet and are relative to Mean Higher High Water (MHHW), Mean Lower Low Water (MLLW), or Mean Sea Level (MSL) datums.


NOAA's Continental US Daily Weather Maps: 1871-2002 September 2002-Present

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Extreme Water Levels - Apra Harbor, Guam, - NOAA Tides & Currents