Chinanews, Beijing, October 27 – According to the China Meteorological Administration, a weak – middle La Nina has formed in the east and central Pacific areas, and it won’t come to an end until early 2008.The previous El Nino ended in last February. Since then, the water temperature in the middle-east Pacific has dropped fiercely, and by last August, it had met the standard of a typical La Nina. Last September, the phenomenon expanded to larger areas. According to the temperature records this month, the average water temperature in that area is 1.3 degrees centigrade lower than the same period in previous years.La Nina usually brings more precipitation in autumn to north China, and the precipitation in northwest China and the south and central part of the Central China Plain hit new highs in last September. The number of rainy days in Gansu, Shaanxi, Shanxi, Hebei and Shandong provinces has been the most since 1951.It can be estimated that it will be very cold this winter, too, due to the effect of the La Nina. Thus farmers should be prepared for possible frost.