January in Santa Rosa averages a daily high of 15°C with nights around 4.6°C. Expect roughly 14.5 wet days totalling 158.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Santa Rosa is May–October.
Based on SANTA ROSA, CA US (1.7km), 1995–2024. 24 years of January data.