December in Viacha averages a daily high of 16.4°C with nights around 3.8°C. Expect roughly 17.4 wet days totalling 96.9mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Viacha is April–November.
Based on EL ALTO INTERNATIONAL, BL (19.1km), 1995–2024. 17 years of December data.