Webaverage annual water temperature on the coast in north topsail beach is 71°f, by the seasons: In winter 61°f, in spring 66°f, in summer 81°f, in autumn 74°f. Webtopsail island, pender county water and sea temperatures for today, this week, this month and this year Webfind out the current water temperature and surf conditions at topsail island beach, surf city, and north topsail beach. See live webcams, monthly average temperatures, and. Webtopsail island water temperatures peak in the range 27 to 29°c (81 to 84°f) on around the 18th of july and are at their minimum on about the 15th of february, in the range 18 to. Webaverage annual water temperature on the coast in topsail beach is 71°f, by the seasons: In winter 61°f, in spring 66°f, in summer 81°f, in autumn 74°f.