September in Sousse averages a daily high of 32.9°C with nights around 20.3°C. Expect roughly 6.2 wet days totalling 47.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Sousse is October–April.
Based on KAIROUAN, TS (51.4km), 1995–2024. 21 years of September data.