Tides are the regular increase and decrease of the water level of the sea under influence of the sun and the moon. The tides caused by the sun and the moon can be very well predicted based on past observations at a location combined with tidal theory. However the tides can be disturbed by current weather conditions.
This website can show a predicted tide level for any location in the world. These predictions are based on satellite observations. For a number of tidal stations more accurate predictions can be made based on local observations of the water height via tide gauges.