December in Semnan averages a daily high of 11.3°C with nights around 2.3°C. Expect roughly 3.6 wet days totalling 17.7mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Semnan is March–April.
Based on SEMNAN, IR (9.4km), 1995–2024. 16 years of December data.