The best times to visit San Francisco are in the spring and fall months of May, June, September and October, when the weather is warm and clear and tourist season isn't at its peak. Traveling to San Francisco in the winter means chilly, damp weather, while in the summer, you'll find hot days, heavier crowds, and higher hotel rates. The best time for outdoor sightseeing and walks around the city is "Indian summer," just after Labor Day weekend through September and into October. After summer, when the skies clear and temperature rises, the beaches are amazing.
One of the most exciting tourist destinations in the world, San Francisco is overall safe, including the walkable neighborhoods of Union Square, Chinatown, Financial District and Fisherman's Wharf. The city also offers safe public transportation, including the nearby cable cars. Tourists should be careful to avoid dark alleyways and rougher downtown districts like the Tenderloin and 6th Street, and always be aware of their surroundings