August in Boulder averages a daily high of 30.3°C with nights around 13.5°C. Expect roughly 9.9 wet days totalling 40.7mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Boulder is September–October.
Based on BOULDER, CO US (2.5km), 1995–2024. 30 years of August data.