September in Mount Pleasant averages a daily high of 29.5°C with nights around 21°C. Expect roughly 8.9 wet days totalling 129.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Mount Pleasant is March–May.
Based on SULLIVANS ISLAND, SC US (3.6km), 1995–2024. 19 years of September data.