September in Bilbao averages a daily high of 24.8°C with nights around 14.1°C. Expect roughly 10.8 wet days totalling 73.5mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Bilbao is May–October.
Based on BILBAO AEROPUERTO, SP (4.2km), 1995–2024. 30 years of September data.