Experts say Typhoon Megi is caused by the La Nina weather phenomemon. La Nina is characterised by unusually cold temperatures in the equatorial Pacific Ocean. It has caused six typhoons this month, with three of them battering the Chinese mainland and Taiwan. The weather phenomenon is predicted to bring further hardship to China later this year, including extremely cold temperatures in winter.

Chief weatherman of National Marine Environmental Forecasting Center, Jiang Hua, said, "One of the requirements of a typhoon forming is that the temperature must be above 26 degrees Celsius. So because this La Nina emerged, the temperature of the Northwest Pacific Ocean is higher than that of previous years. That is a condition favorable to the formation of a typhoon. High sea temperatures will lead to a larger thermal difference between land and sea. This will bring stronger winds from the north, pushing down temperatures in winter."