Abstract:Using station observation data and the NCEP/NCAR reanalysis data, this paper analyzes the main climatic characteristics, large-scale atmospheric circulation anomalies, and East Asian winter monsoon features in China during the winter of 2025/2026 (December 2025 to February 2026), with a focus on the causes of the abnormally active sand-dust weather in February 2026. The results show that in the winter of 2025/2026, the national average temperature was -1.5℃, which is 1.5℃ higher than the climatological average, ranking as the second highest for the same period since 1961. The national average precipitation was 27.4 mm, 35.3% less than normal, with a spatial distribution of more precipitation anomaly in the north and less in the south. The 500 hPa geopotential height field over the mid-high latitudes of Eurasia was dominated by a zonal circulation, the westerly was in a relatively straight pattern, and the East Asian winter monsoon was weaker than normal. During the 2025/2026 winter, a total of six sand-dust weather events occurred in China, 4.2 times more than the climatological average. Among them, there were three sandstorm events, which was 2.7 times more than the climatological average (0.3 times). Moreover, the number of sand-dust days reached 7.7 d, the highest in winter since 1991. The analysis on the formation causes of sand-dust weather indicates that the sand source areas experienced significantly warm and dry conditions in this winter. Precipitation was below average but temperature was above average. This situation led to low vegetation coverage and a substantial reduction in surface resistance to wind erosion, thereby providing abundant material conditions for sandstorms. Against this background, the synergistic effect of strong cold air and the Mongolian cyclone generated a large pressure gradient triggering extreme gale winds. This condition, combined with enhanced thermal lifting due to large temperature differences between upper and lower levels, resulted in large amounts of sands and dusts being lifted into the atmosphere and transported to downwind areas. Besides, global climate warming has further exacerbated the drying trend in the sand source regions, increasing the frequency of the superposition of such warm-dry conditions with intense weather processes.