August in Thornton averages a daily high of 31.9°C with nights around 14°C. Expect roughly 7.4 wet days totalling 32.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Thornton is September–October.
Based on NORTHGLENN, CO US (4.9km), 1995–2024. 30 years of August data.