Pack or skip
Sunscreen for San Francisco in September
Verdict
Pack it
Sun still finds you at 70°F — UV doesn't care about temperature.
Why
San Francisco in September averages highs of 70°F, lows of 57°F, 2 rainy days.
That climate means sunscreen earns its space in the bag. Sun still finds you at 70°F — UV doesn't care about temperature.