Caution: The forecast below is experimental and no promise of accuracy is implied; especially, the forecast is explicitly not accurate when either a tsunami, tropical storm or hurricane warning is in effect. In these latter cases, see either tsunamis or tropical storms/hurricanes.

Red Line at Top |
Indicates the sea level height that is exceeded by two percent of the observed daily Higher High Waters (HHW description) based on a 19-year historical record (excluding tsunamis). |
Vertical Yellow Line | Time this forecast was created. |
Dark Blue Curve | Observed Sea Level at Hilo Hbr. for previous 3 days. The measurement is relative to MLLW (Mean Low Low Water), a well-defined reference level (NOAA datum description) |
Cyan Curve | Forecast Sea Level at Hilo Hbr. for next 6 days. The forecast is relative to MLLW, and includes tides plus multi-day sea level variations. The forecast is updated every four hours. |
Click here for additional information about both the plotted variables and forecast accuracy.
Click here for the detailed technical report explaining the methods for producing the PacIOOS High Sea Level Forecasts.