September in Lisburn averages a daily high of 16.2°C with nights around 9.3°C. Expect roughly 15.5 wet days totalling 71.3mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Lisburn is June–September.
Based on HILLSBOROUGH, UK (8.3km), 1995–2024. 23 years of September data.