The main characteristics of the general atmospheric circulation in summer 2020 (from June to August) are as follows. The polar vortex is characterized by a monopole pattern in the Northern Hemisphere, which centers in the Arctic Circle toward the Eastern Hemisphere. The circulations in the middle and high latitudes present a 4-wave mode. Due to the anomalously strong western Pacific subtropical high that lies westward and southward, there are fewer tropical cyclone activities in June and July than in normal years. There are totally 8 tropical cyclones generated over western North Pacific and the South China Sea in this summer, while none is generated in July. Except for western North Pacific and the South China Sea, there are 20 tropical cyclones in other oceans, including 11 in the North Atlantic, 8 in the East Pacific, and one in the North Indian Ocean. The warm and moist southerly winds bring about several sea fog events in the northern seas, and there are more sea gales under the impacts of the cyclones moving into the sea. There are 7 obvious sea fog events over offshore areas in the summer, including three in June, one in July, and three in August. There are 10 gale processes over offshore areas, among which two are related to tropical cyclones and 7 are caused by extratropical cyclones. Twelve rough sea wave events above 2 m occur over offshore areas with 4, 5 and three in June, July, and August, respectively.