Today's Sea Island sea temperature is 86 °F. Statistics for 28 Aug (1981–2005) – mean: 83 °F, range: 81 °F to 84 °F. Very warm air temperatures and very warm water(86 °F) too at Sea Island, warm enough for wearing board shorts and a rash vest in the surf. Cloudy, but feeling very pleasant in and out of the water. (click thumbnails to expand) Below is a graph of Historical Sea Surface Temperature for Sea Island.