surrounded by water in three sides. Due to the influence of California Current on the Atlantic Ocean, San Francisco has the typical Mediterranean Climate with cool summer. Due to long-term influence by the sea wind, the high temperature in the summer of usually about 20 degrees Celsius, and there is only about one week with the temperature higher than 30 degrees Celsius due to strong land wind in a year. September is the warmest month. In addition, since the water temperature in the Pacific Ocean is 10 to 15 degrees Celsius all year round, the temperature in the midnight of the summer might reduce to the level below 10 degrees Celsius. Adjacent to the sea and Golden Gate strait, frequently influenced by fog in the latter half of night and the morning. But it seldom rains in the summer. The rainy season is from January to the middle of April. Though it is cold in the winter, it hardly snows.