Hangzhou is located in the southern part of the Yangtze River Delta, at the western end of Hangzhou Bay, in the lower reaches of the Qiantang River, and at the southern end of Beijing-Hangzhou Grand Canal. It is an important and central city in the Yangtze River Delta and a traffic hub in southeast China. The geographic coordinates of the center of Hangzhou proper are 30°16' north and 120°12' east. The northwest and southwest of Hangzhou fall under the West and Central Zhejiang hilly region, while the northeast and southeast fall under the North Zhejiang Plain with dense river networks, making it a part of the famous land of fish and rice. The hilly land of the city accounts for 65.6% of the total area, the plain 26.4%, rivers, lakes, ponds, reservoirs, etc. 8%. Under the subtropical and monsoon conditions, Hangzhou has four distinct seasons with a mild and humid climate and plentiful sunshine and rainfall. The average temperature is 16.2℃ around the year, 28.6℃ in summer and 3.8℃ in winter. The number of frost-free days is between 230 and 260. The average annual rainfall is 1,435 mm and the average relative humidity 76%.