Sullivan's Island water temperature by month

Jellyfish season

What usually turns up on the South Carolina coast, and when.

• The sea nettle is the summer one. South Carolina’s Department of Natural Resources calls it common in the summer and says this species causes most of the jellyfish stings that occur in South Carolina waters. South Carolina's Department of Natural Resources — Sea Science: jellyfish
• Cannonball jellies are the harmless crowd: during the summer and fall, large numbers appear near the coast and in the mouths of the estuaries, and they are one of the least venomous jellyfish here. South Carolina's Department of Natural Resources — Sea Science: jellyfish
• Winter has its own. The lion’s mane — the winter jelly — typically appears during the colder months. South Carolina's Department of Natural Resources — Sea Science: jellyfish
• The Portuguese man-of-war is a visitor rather than a resident here. It lives in the tropics, the subtropics and the Gulf Stream, and only drifts into nearshore South Carolina water infrequently, pushed by wind and current. South Carolina's Department of Natural Resources — Sea Science: jellyfish

This is what a season usually looks like, not a forecast of any particular week. Jellyfish drift on wind and current, so the people who watch them say there are tendencies but no guarantees — the lifeguard flags on the day beat any calendar.