September in Plymouth averages a daily high of 18.7°C with nights around 11.8°C. Expect roughly 12.6 wet days totalling 70.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Plymouth is June–September.
Based on PLYMOUTH MOUNTBATTEN, UK (2.5km), 1995–2024. 30 years of September data.