October in Fountain Valley averages a daily high of 25.3°C with nights around 15.8°C. Expect roughly 3.1 wet days totalling 15.4mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Fountain Valley is April–November.
Based on SANTA ANA JOHN WAYNE AIRPORT, CA US (8.6km), 1995–2024. 26 years of October data.