Crossed by the Tropic of Cancer in the central part of its continental portion, tropical and sub-tropical Guangdong has a climate marked by high temperature and plentiful rainfall. It has the highest mean annual temperature of any province which increases from 19ºC. in the north to 25ºC. on Hainan Island. With the exception of the highlands in the north, the province has long summers and no winters and is green all year round. Thanks to the breeze from the ocean, it is generally cooler in Guangdong than in the middle Yangtze River valley. The Leizhou Peninsula and Hainan Island are in the tropics where tropical plants grow in profusion. The greater part of the province has a mean annual precipitation of more than 1,500 mm. and 140-160 rainy days. The coastal regions are frequently visited by typhoons between May and November.