August in Rijeka averages a daily high of 29.9°C with nights around 19.8°C. Expect roughly 7.9 wet days totalling 100.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Rijeka is May–June.
Based on RIJEKA, HR (0.9km), 1995–2024. 29 years of August data.