The main characteristics of the general atmospheric circulation in spring 2021 (from March to May) are as follows. The polar vortex is characterized by a dipole pattern in the Northern Hemisphere and is stronger than average. The westerlies in the middle and high latitudes are in 4-wave pattern. In March, the intensity of southward cold air is weak, leading to frequent sea fog processes. In April, the northern sea area is affected by a high pressure system, the low-level circulation is stable, thus the activity of cold air is weak. In May, due to the influence of extratropical cyclones, there are gale weather processes over offshore areas of China. There are totally 5 gale processes above 8-grade over offshore areas of China in spring, including 2 produced by cold air, 1 jointly induced by cold air and extratropical cyclones, and 2 generated by extratropical cyclones. Eight obvious sea fog processes occur over offshore areas, including three in March, two in April, and three in May. There are 8 rough sea wave processes above two meters, and days of rough sea wave processes are less. Two tropical cyclones are active over westem North Pacific and the South China Sea. The sea surface temperature in the offshore areas of China shows an overall rising trend, while the increasing rates in eastern and southern sea areas are obviously higher, which enhances the sea surface temperature north-south gradient.