Understanding the ocean
The tides are a regular and predictable phenomenon caused by the gravitational
attraction of the moon and the sun acting on the oceans of the rotating earth. This results in regular periodic and predictable movement of the water in the seas and oceans. You should not confuse this with the more unpredictable movements caused by meteorological conditions (winds and changes in atmospheric pressure) which are called surges. Surges can only be predicted a few days ahead (just like the weather) and with considerably less accuracy than
the tides. The tide must be added to the surge and waves to give a total water level.
Tides are caused purely by the moon, the sun and the coastline and seabed topography. Unless the shape of the coastline or seabed changes dramatically, the tides can be predicted accurately many years in advance.