December in Manteca averages a daily high of 13.8°C with nights around 3.6°C. Expect roughly 9.6 wet days totalling 70.7mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Manteca is April–May.
Based on STOCKTON AIRPORT, CA US (10.3km), 1995–2024. 30 years of December data.