“The coldest winter I ever spent was a summer in San Francisco” -Mark Twain Although this is California, San Francisco is notorious for its fog and subsequent chilly weather, remember to wear layers.
San Francisco is famous for its steep hills. Although attractions may appear close together on a map, be weary that you might have to climb rather strenuous hills.
Parking in San Francisco is tough, there are many lots throughout the city but these can be rather expensive. Consider trying BART or muni, although they are not the most extensive public transit systems.
While there are some stunning beaches in San Francisco, be careful swimming. The water is cold and the rip tides are strong. Some people certainly do swim or surf, but be cautious.
If you are a wine enthusiast, definitely take a day trip to Sonoma or Napa Valley for some of the best wine in the country.