Will I be cold?
Will I be cold in San Diego in October?
Verdict
No — No, comfortable.
Lows stay near 63°F — you won't be reaching for the puffer.
Day vs. night
Day
77°F
Warm
Breathable fabrics; sunscreen matters more than a jacket.
Night
63°F
Comfortable
Comfortable outside without an extra layer.
Why
San Diego in October averages highs of 77°F, lows of 63°F, 2 rainy days.
You can pack for the daytime temps and not worry about the evening dip.