Surrounded on three sides by water, San Francisco's weather is strongly influenced by the cool currents of the Pacific Ocean, moderating temperatures and producing a consistently mild year-round Mediterranean climate, with cool, wet winters and dry summers.
While it rarely gets more than 5 to 10 degrees on either side of 60º F, San Francisco does get cool once the sun goes down or the fog rolls in, so we recommend bringing layers. In summer, be prepared for daily morning and evening fogs. In winter, an umbrella and raincoat come in handy for sudden downpours. September and October are usually our warmest and driest months.
Any season is good season for a visit to San Francisco!