Just be sure to carry a light jacket with you.  The temperatures in SF swing pretty dramatically during the course of a day.  It can be low to mid 50 degrees farenheit in the morning, mid 70's in the day and back down into the 50's as the evening wears on.  It feels a bit cooler than that when the fog rolls in or if it's misting rain.

The natives will tell you to layer your clothing, for good reason.  :)