I'm on the outskirts of SF Bay Area. I don't know of any stamp or craft stores in the city. There are lots of Michaels (big craft store) in the suburbs. Are you busy the whole week? You could take BART (rapid transit train) out my way and I could take you to Stampers Warehouse
www.stamperswarehouse.com , but that would eat up a good portion of a day. What sort of things are you planning to do? Let me know if I can help with ideas.
Oh, are you familiar with the Mark Twain quote: "The coldest winter I ever spent was a summer in San Francisco." It could be a nice 80 degrees out my way and in the cool 60s in SF. The ocean breezes and fog keeps it cool there. So, dress in layers.
~ Kathy