Why is it so sultry recently?

This is a geographical problem, hehe. Under normal circumstances, the subtropical high should move northward,

The specific principles are as follows: I hope I can help you!

Generally speaking, the western Pacific subtropical high moves regularly from south to north from winter to summer every year; From summer to winter, it retreats regularly from north to south. Affected by the distribution of land and sea, the warm and high pressure area in the transitional zone between tropical and temperate zones often splits into several isolated warm and high pressures, which are collectively called subtropical high. This high pressure is a large-scale weather system that controls tropical and subtropical regions for a long time, and its position and intensity change with seasons. The subtropical high that affects China mainly includes the western Pacific high, the Qinghai-Tibet high and the South China Sea high, among which the western Pacific high has the greatest influence on China and is one of the main weather systems that cause drought and flood changes in summer. The weather conditions in different parts of the subtropical high are different.

In the subtropical high pressure area, the weather is generally sunny, so when it controls a certain area for a long time, it will often cause long-term high temperature and drought in the area, but when the conditions are right, local geothermal thunderstorms sometimes occur; On the south side of the western Pacific high, typhoons are frequent. In its easterly airflow, easterly waves often form and move westward, affecting Guizhou, the east of Guangxi and the south of the Yangtze River, causing thunderstorms and heavy rains. On the north and northwest side of the subtropical high, a large amount of water vapor is brought from the sea because of the southerly airflow in the west. When there is a trough or vortex weather system in the westerly belt, it will produce a wide range of rain belt. According to statistics, this rain belt is located in the area of latitude 5- 18 north of the western ridge line of the western Pacific high, and it is generally east-west. The rainy season in South China, Jianghuai and North China are all closely related to the northward movement of the western Pacific high. The length of time that this rain belt stays in a certain area is directly related to the drought and flood in this area. Generally speaking, the longer the rain belt stops, the more floods will occur. The more times of waterlogging, the shorter the residence time, and the more prone to drought. The location of the Qinghai-Tibet high is closely related to the plum rains in the Yangtze River basin and the heavy rains in Shaanxi, Qinghai and Gansu.