Why is it the middle and late September, and the highest temperature in Hangzhou during the day is still above 30 degrees?

The latitude of Hangzhou is about 30 degrees north latitude. 10 is the time when the subtropical high recedes into the sea. Under the control of high pressure, the autumn is crisp and sunny, so the temperature can be maintained above 30 degrees during the day. But at night, the ground loses heat quickly, and the temperature at night and early morning is much lower than during the day, which makes it cool in the morning and evening. 1 1 month comes, the sunshine time becomes shorter, and the cold air in the north strengthens southward, during the day.