Shanghai has a humid subtropical climate (Köppen Cfa) and experiences four distinct seasons. Winters are chilly and damp, with northwesterly winds from Siberia can cause nighttime temperatures to drop below freezing, although most years there are only one or two days of snowfall. Summers are hot and humid, with an average of 8.7 days exceeding 35 °C (95 °F) annually; occasional downpours or freak thunderstorms can be expected. The city is also susceptible to typhoons in summer and the beginning of autumn, none of which in recent years has caused considerable damage. The most pleasant seasons are spring, although changeable and often rainy, and autumn, which is generally sunny and dry. The city averages 4.2 °C (39.6 °F) in January and 27.9 °C (82.2 °F) in July, for an annual mean of 16.1 °C (61.0 °F). With monthly percent possible sunshine ranging from 34% in March to 54% in August, the city receives 1,895 hours of bright sunshine annually. Extremes since 1951 have ranged from −10.1 °C (14 °F) on 31 January 1977 (unofficial record of −12.1 °C (10 °F) was set on 19 January 1893) to 39.9 °C (104 °F) on 6 and 8 August 2013. A highest record of 40.8 °C (105 °F) was registered in another station on 7 August 2013.
Shanghai lies on China’s east coast roughly equidistant fromBeijing and Guangzhou. The Old City and modern downtown Shanghai are now located in the center of an expanding peninsula between the Yangtze River Delta to the north and Hangzhou Bay to the south, formed by the Yangtze’s natural deposition and by modernland reclamation projects. The provincial-level Municipality of Shanghai administers both the eastern area of this peninsula and many of its surrounding islands. It is bordered on the north and west by Jiangsu, on the south by Zhejiang, and on the east by theEast China Sea. Its northernmost point is on Chongming Island, now the second-largest island in mainland China after its expansion during the 20th century. The municipality does not, however, include an exclave of Jiangsu on northern Chongming or the two islands forming Shanghai’s Yangshan Port, which are part of Zhejiang’s Shengsi County. This deep-water port was made necessary by the increasing size of container ships but also the silting of the Yangtze, which narrows to less than 20 meters (66 ft) as far out as 45 miles (70 km) from Hengsha.
Downtown Shanghai is bisected by the Huangpu River, a man-made tributary of the Yangtze that was created by order of Lord Chunshen during the Warring States period. The historic center of the city was located on the west bank of the Huangpu (Puxi), near the mouth ofSuzhou Creek, connecting it with Lake Tai and the Grand Canal. The central financial districtLujiazui has grown up on the east bank of the Huangpu (Pudong). The destruction of local wetlands occasioned by the creation of Pudong International Airport along the peninsula’s eastern shore has been somewhat offset by the protection and expansion of the nearby shoals of Jiuduansha as a nature preserve.
Shanghai’s location on an alluvial plain means that the vast majority of its 6,340.5 km2 (2,448.1 sq mi) land area is flat, with an average elevation of 4 m (13 ft). Its sandy soil has required its skyscrapers to be built with deep concrete piles to stop them from sinking into the soft ground of the central area. The few hills such as She Shan lie to the southwest and the highest point is the peak of Dajinshan Island in Hangzhou Bay (103 m or 338 ft). The city has many rivers, canals, streams and lakes and is known for its rich water resources as part of the Lake Tai drainage area.