Abstract:The main characteristics of the atmospheric circulation in the Northern Hemisphere in February 2025 are as follows. The polar vortex was distributed in a dipole-shaped pattern. The polar vortex in the Eastern Hemisphere, located over the central Siberian Plateau to the Sea of Okhotsk, was weaker than normal, and a low vortex which was split from the polar vortex controlled the mid-latitude northwestern Pacific Region. The average trough above the eastern part of East Asia was stronger than usual, and the southern branch trough was more eastward and active. The national mean temperature in February was 0.4℃ lower than in the same period of previous years, while the mean temperatures in southern part of Northeast China, central Inner Mongolia, northern part of North China, western Guizhou Province and western Guangxi Province were 2-4℃ lower than usual. The national average precipitation was about 35% less than normal. The precipitation in Xinjiang, west-central Inner Mongolia, North China, the west-central part of the Huanghuai Region, the Jianghuai Region, and the east-central part of South China was more than 80% less than usual. However, most parts of Southwest China and the east-central part of Northwest China received precipitation more than doubled. During this month, cold air activities occurred frequently and there were two strong cold air processes and one cold wave event, among which the cold wave from 6 to 8 February caused a sharp drop in temperature and significant low temperature. The southern branch trough guided the warm-moist air from low latitudes to flow into southern China, where it joined the southward-moving cold air, leading to five large-scale rain and snow events. Overall, the key challenge in forecasting lies in how to timely use multi-source observational real-time data within medium- and short-term lead time period to conduct forecast verification, adjust intensity and movement paths of high- and low-level systems, and improve the accuracy of temperature drop and precipitation forecasts.