July in Boulder averages a daily high of 31.4°C with nights around 14.3°C. Expect roughly 10.6 wet days totalling 47.7mm. 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 July data.