San Francisco's weather is as changeable as the seas, literally. Surrounded on all sides (save one) by ocean and bay, San Francisco's weather is also one of the hardest to forecast and changes drastically from neighborhood to neighborhood. Over four seasons, not one of which corresponds to its climatic expectations, San Francisco's weather can be difficult for visitors to predict, save that Fog City delivers majestic skies, trademark plumes of white fog and brilliant sunsets.
San Francisco summers have little in common with summers elsewhere. Marked by billowing white fog, the majestic product of sea spray, wind and Central Valley heat, San Francisco summers are characteristically overcast and cool, while the marine layer usually burns off by the afternoon. Days can be warm, but the evening fog comes in suddenly and can be extremely cold. While one part of the City can be shrouded in fog, another is in warm sunshine. The average temperature in July is between 55-70 degrees Farenheit.
San Franciscans traditionally dress in "layers" to adjust to the changing conditions.
Please be prepared by bringing a coat and a sweater and long pants.