Pack or skip
Sunscreen for Washington DC in September
Verdict
Pack it
Sun still finds you at 79°F — UV doesn't care about temperature.
Why
Washington DC in September averages highs of 79°F, lows of 62°F, 6 rainy days.
That climate means sunscreen earns its space in the bag. Sun still finds you at 79°F — UV doesn't care about temperature.