Long term, Denver averages 2" in July and 1.7" in August. So I'd say for this area anyway, on average it peaks second half of July and is often basically over by second half of August.
That being said, there have been many times where August has been much wetter than July (2022 is the only real recent example, but quite a few further back). We are badly due for a very wet August for the region...the last one was 2008.
Of course, we had the wettest September and month ever in 2013, which was due to unusually late monsoonal activity.