Pack or skip
Flip-flops for Denver in September
Verdict
Optional
Warm enough to wear in the evening or on the beach; not on a city walking day.
Why
Denver in September averages highs of 77°F, lows of 48°F, 7 rainy days.
That climate makes flip-flops a judgment call. Warm enough to wear in the evening or on the beach; not on a city walking day.