Review a tide table. Tide tables are available online or in a local newspaper. Tide tables give an accurate prediction of the time of day a high tide will occur, in addition to other information, such as the predicted size of the waves and the water temperature. Tide tables are accurate because the tables use the astronomical positions of the sun, moon and earth to predict when high tide will occur.
Determine the position of the moon. If you are on the coast and the moon is directly overhead, you will experience a high tide. The gravitational force of the moon overhead causes the coastline directly under the moon to experience high tide.
Examine whether the tide is going in or out by looking at the beach for the line of water in the sand. If you notice the waves are crashing farther and farther inland, then the tide is likely coming in. In addition, the ocean may leave a line of debris during high tide to mark the highest point of the high tide.