May in Petaluma averages a daily high of 22.3°C with nights around 8.7°C. Expect roughly 3.5 wet days totalling 22.6mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Petaluma is May–October.
Based on PETALUMA AIRPORT, CA US (3.8km), 1995–2024. 27 years of May data.