Why is the weather in Chengdu so strange?

Chengdu is located in the middle reaches of Minjiang River in the west of Sichuan Basin, with an altitude of 387-5364 meters, with Longquan Mountain in the east and Qionglai Mountain in the west. In the west, Longmen Mountain runs through the north and south. Plain area accounts for 36.4%, hilly area accounts for 30.4%, and mountainous area accounts for 33.2%. The plain area is high in northwest and low in southeast, with an average slope of 0.3%. It has a subtropical humid monsoon climate with four distinct seasons, no intense heat in summer and no severe cold in winter, and the annual average temperature is 16.7℃. The annual average sunshine hours 107 1 hour, and the annual average rainfall of 945.6 mm Chengdu is located in the east of Chengdu Plain, with an average elevation of about 500 meters. Chengdu Plain is the largest plain in southwest China. Dujiangyan Water Conservancy Project, located on the main stream of Minjiang River, has a fan-shaped irrigation canal network distributed on the vast Chengdu Plain, making Chengdu Plain a "land of plenty" where "floods and droughts follow people and hunger is not enough".

Chengdu has a subtropical monsoon climate, characterized by early spring, hot summer, cool autumn and warm winter. The annual average temperature is 16℃, and the annual rainfall is about1000 mm. A remarkable feature of Chengdu's climate is cloudy and short sunshine time. The folk proverb "Shu dog barks at the sun" is an image description of this climate feature. Another notable feature of Chengdu's climate is humid air. Therefore, although the temperature is not high in summer (the highest temperature generally does not exceed 35 degrees Celsius), it seems sultry. In winter, the average temperature is above 5 degrees Celsius, but it looks very cold because of cloudy days and humid air. The rain in Chengdu is concentrated in July and August, and there is less rain and less ice and snow in winter and spring.