December in San Francisco averages a daily high of 14.7°C with nights around 8.7°C. Expect roughly 12 wet days totalling 135.3mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit San Francisco is June–October.
Based on SAN FRANCISCO DOWNTOWN, CA US (0.8km), 1995–2024. 30 years of December data.