December in Rijeka averages a daily high of 11°C with nights around 4.7°C. Expect roughly 11 wet days totalling 178.3mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Rijeka is May–June.
Based on RIJEKA, HR (0.9km), 1995–2024. 29 years of December data.