How to read a tide chart
A tide chart lists the predicted times of high and low water at one tide station, and how high the water will be at each, in feet. Everything else on a chart (curves, calendars, "best time" windows) is built from those few numbers.
Highs, lows and heights
Each row is one turning point of the tide. High is the moment the water stops rising; low is the moment it stops falling. The height is measured in feet above a fixed zero called MLLW, so a low of 0.5 ft is half a foot above that zero and a low of −0.3 ft is a "minus tide", below it.
Here are three days at Springmaid Pier, Myrtle Beach, the gauge used for Myrtle Beach:
| Day | Tides (EST) |
|---|---|
| Sunday, November 15, 2026 | Low 4:44 am (1.2 ft) · High 11:21 am (5.0 ft) · Low 5:34 pm (1.3 ft) · High 11:36 pm (4.1 ft) |
| Monday, November 16, 2026 | Low 5:31 am (1.3 ft) · High 12:11 pm (4.9 ft) · Low 6:22 pm (1.3 ft) |
| Tuesday, November 17, 2026 | High 12:29 am (4.2 ft) · Low 6:25 am (1.4 ft) · High 12:59 pm (4.9 ft) · Low 7:13 pm (1.2 ft) |
Why the times move later every day
The main driver of the tide is the moon, and the moon comes back over the same spot about every 24 hours and 50 minutes. So on most coasts each high tide arrives roughly 50 minutes later than the day before. At Springmaid Pier, the first high tide of Monday, November 16, 2026 comes 50 minutes later than the day before. That drift is why a tide table is only good for the dates printed on it.
Two tides a day, or one
- Atlantic beaches usually get two highs and two lows a day of similar height, about 12 hours 25 minutes apart.
- Pacific beaches also get two of each, but the two highs (and the two lows) are often quite different heights. At La Jolla on Sunday, November 15, 2026, the highs are 4.5 ft.
- Gulf beaches often get just one high and one low a day, and the range is small. At Galveston, 11 of the 21 days from Sunday, November 15, 2026 have a single high tide.
So a day with three tides listed is not a mistake: the fourth turning point fell just before midnight or just after.
Reading the curve
Our town pages draw a curve through the predicted highs and lows. NOAA publishes the turning points; the shape between them is our interpolation (a smooth cosine), close to how the water moves on most beaches but not exact. Night is shaded, and the sand-coloured bands show the daylight hours when the water is near low tide, usually the widest beach of the day.
Predictions, not observations
Tide tables are astronomical predictions. Strong onshore wind, a storm or low air pressure can push the real water level well above the prediction, and offshore wind can hold it below. Where a station reports live water level, our town page shows the observed level next to the prediction. Tide charts here are for the beach, not for navigation.