Extreme low temperature, heavy snowstorm and frost disasters occurred in China i n January of 2008. The disasters are unprecedented owing to their nationalwide influences, their infrequent intensity, and the long lasting periods of the low temperature, snowstorm and frost days. They led to huge losses in the country. In the second part of this paper, the possible climatic causes are analyzed. Res ults show that the La Nina event began in August 2007 and developed very quickly . It led to the anomalous general circulations in the Northern Hemisphere, which was thought to be the most important causes of unprecedented disasters. In Janu ary, the geopotential height over the Ural was abnormally high while the count erpart over the Middle Asia, the Mongolia and the Far East regions of the Russia was low. This pattern is propitious to the cold air activity from the high lati tudes. In that month, the western Pacific subtropical high (WPSTH) located more northward, which favors the transportation of the warm and wet moisture to China along its west and north sides. The position of the WPSTH determined the disast er regions. In addition, the Indian and Burma trough (IBT) in the south side of the QinghaiXizang Plateau is quite active, which favors the moisture transport ation in another way to China, i.e., along the YunnanGuizhou Plateau from the Indian Ocean and the Bay of Bengal. Results also indicate that the inversion lay er in that month was the strongest in all Januaries since 1951 and its persisten ce was the main causes of the frozen rain in Hu'nan and Guizhou provinces.