September in Mandurah averages a daily high of 19.3°C with nights around 11.9°C. Expect roughly 12.3 wet days totalling 58.6mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Mandurah is October–April.
Based on MANDURAH, AS (1.1km), 1995–2024. 23 years of September data.