Significant Wave Height (Climatology)

Significant wave height climatology is the long-term statistical description of significant wave height (Hs), the mean height of the highest one-third of waves, equal to four times the standard deviation of the sea-surface elevation. Climatologies built from satellite altimeters since 1985, buoy networks, and wave-model reanalyses such as ERA5 give monthly means, percentiles, and return-period extremes by location. Open Southern Ocean means exceed 4 to 5 m while sheltered seas stay near 1 m. Designers use the 50- and 100-year Hs return values for offshore structures and ships, and route planners use the seasonal fields.