September in Mustamäe averages a daily high of 16.3°C with nights around 8.6°C. Expect roughly 12.3 wet days totalling 57.9mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Mustamäe is June–August.
Based on TALLINN, EN (4.5km), 1995–2024. 29 years of September data.