South Carolina

South Carolina's Lowcountry coast — Charleston Harbor, Folly Beach, the Stono inlets, the long ribbon of barrier islands and tidal marshes south of Cape Hatteras — runs a clean semidiurnal tide with a moderate range. Charleston Harbor sits at about 1.7 metres mean range, two highs and two lows of comparable size each day, twelve and a half hours apart. Spring tides push toward 2.0 metres and the marsh creeks behind Folly and the Stono inlet run hard on every ebb. Shell-hunting along Folly's intertidal zone is best on the lowest predicted lows, which cluster around new and full moons; an hour either side of a sub-0.3 metre low gives a wide walkable washline. Marsh-creek paddlers time their out-and-back to the rising flood. Hurricane season runs June through November, and a tropical-storm surge can stack one to two metres above predicted on top of normal tide — that is when emergency-management forecasts override everything else. The harmonic predictions on this site assume normal weather.