December in Arecibo averages a daily high of 27°C with nights around 17.8°C. Expect roughly 13.7 wet days totalling 119.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Arecibo is December–March.
Based on ARECIBO OBSERVATORY, PR US (14.2km), 1995–2024. 26 years of December data.