August in Oslo averages a daily high of 21.6°C with nights around 12.7°C. Expect roughly 13.3 wet days totalling 104.9mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Oslo is June–September.
Based on OSLO BLINDERN, NO (3.6km), 1995–2024. 30 years of August data.