Tidal variation is the factor that most determines when to go surfing. Wave shape and the whole pattern of the surf changes with the tide, more or less hour to hour. On successive days, the tides are an hour later each day because the moon orbits the planet in the same direction as the planet spins. Since the moon advances in its orbit during the course of a day, it takes about an hour extra for your location to catch up to the moon and the tide that follows it.
Since the phases of the moon concern its position relative to the lit side of the earth, the timing of the tide reflects the lunar cycle. In the course of a week following a full or new moon, high tides occur during the middle of the day and the middle of the night. For instance, at the beginning of the week following a full moon, high tide is in the middle of the morning. Since the tide returns about an hour later than it did the day before, by the end of the week, high tide is late in the afternoon, as a low tide week begins.
Tidal variations vary greatly across the globe. For example, the tidal range in Hawaii is typically less than one meter. However, Indonesia, Panama and Ireland experience 2-3 meter tide fluctuations. Such extreme tidal variation has a major affect on surf conditions. So, surf travelers have to take it into account, when deciding on the best time to book a surf trip. This was the inspiration behind Dan Webber's interactive multimedia design for displaying tide graphs. Despite providing insight into tidal variation, the innovation failed to find a market; possibly because surf travel providers don't really stand to gain from providing such detailed information.