The tide, the Sun, the Moon and the stars over the harbor, worked out in your browser from the motions of the Earth, Moon and Sun. There is no data feed. Tested against NOAA, it lands all 2,821 high and low tides of 2026 and 2027 within a minute and a fifth of an inch.
Feet above mean lower low water, the zero on Charleston's tide gauge. Shaded bands are night. Dashed lines are the National Weather Service flood stages for the harbor gauge.
The next eight tides from the selected moment. Left: computed here, live. Right: NOAA's published prediction for the same station.
| Charleston time | Tide | Here | NOAA | Time diff | Height diff |
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The six highest astronomical tides in the twelve months after the selected moment. Wind and rain add to these.
Charleston's tide is the sum of 37 steady waves, each one tied to a motion in the sky: the Moon's pull twice a day, the Sun's, the Moon's tilt, the ellipse of its orbit, the season. NOAA measured how big each wave is at this gauge and when it crests. That table of 37 sizes and timings is the only local data on this page.
Everything else is astronomy. For any instant, the page computes where the Moon, the Sun, the Moon's perigee and the Moon's orbital node are, turns those into the phase of each of the 37 waves, and adds them up. The node matters: the Moon's orbit wobbles on an 18.61-year cycle, and right now it makes Charleston's main lunar tide a few percent its long-run average.
The sky uses the same clock. The Sun and Moon come from classical orbital series, corrected for the Moon's closeness to Earth and for the air bending light near the horizon. The Moon's lit side is drawn at the real tilt for this spot. The stars are real ones at their real positions, turning with sidereal time.
This is the astronomical tide, the same quantity NOAA publishes. Wind, rain, river flow and storm surge come on top, which is why the Weather Service issues its own total water forecast before a flood. You can enter any date from 1900 to 2100.