Chinese authorities are being urged to prepare for extreme weather during the coming months as El Nino conditions impact seasonal weather patterns. Unusually warm ocean temperatures caused by El Nino have been influencing China\'s weather since July and will continue to do so into the fall, China\'s state-run Xinhua news agency reported Zheng Guoguang, director of the China Meteorological Administration, as saying. Heavy rains are likely in the middle and eastern parts of China through August, Zheng said, calling for strengthened flood control efforts in the Haihe River Basin in north China and along the middle and lower reaches of the Yellow and Yangtze rivers. Meanwhile in areas south of the Yangtze River local authorities should take precautions against summer droughts and arid weather, Zheng said. El Nino\'s abnormal warming of the sea surface in the Equatorial Pacific can cause exceptionally heavy rainfall in some parts of the world and extreme droughts in others. Such conditions occur every two to seven years, with stronger El Nino events generally occurring every 10 to 15 years.