December in San Diego averages a daily high of 18.7°C with nights around 9.8°C. Expect roughly 5.6 wet days totalling 41.6mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit San Diego is April–November.
Based on SAN DIEGO INTERNATIONAL AIRPORT, CA US (2.6km), 1995–2024. 30 years of December data.