Wuhan's climate is humid subtropical (Koppen Cfa) with abundant rainfall and four distinctive seasons. Wuhan is known for its oppressively humid summers, when dewpoints can often reach 26 °C (79 °F) or more. Because of its hot summer weather, Wuhan is commonly known as one of the Three Furnaces of China, along with Nanjing and Chongqing. Spring and autumn are generally mild, while winter is cool with occasional snow. In the recent thirty years, the average annual rainfall is 1269 mm, mainly from June to August; annual temperature is 15.8℃-17.5℃, annual frost free period lasts 211 to 272 days and annual sunlight duration is 1810 to 2100 hours. Extreme temperatures have ranged from −18.1 °C (−1 °F) to 42.0 °C (108 °F)
