For the most part a pair of Levi’s blue jeans (which were invented in San Francisco) and a light windbreaker or sweater will handle most wardrobe necessities in San Francisco. Temperatures seldom rise above 70° F (21°C) or fall below 40°F (5° C). San Francisco has a temperate marine climate an enjoys mild weather year-round. Morning and evening fog rolls in during the summer months but rarely persists.
August through October are the warmest months of the year, but for the most part, dressing in layers is recommended. The weather can change by the hour (and within just a few blocks), so keep a that windbreaker or light jacket handy. Comfortable shoes are a must, too. San Francisco is best explored on foot.
And most important of all, pack your spontaneous side. You never know what adventures might be just around the next corner.