Why is it so hot in Nanjing in summer?

1. There are many hills in the south and east of Nanjing, and it is difficult for southeast winds to enter in summer.

To the north of Nanjing is the Yangtze River, and Xuanwu Lake is very humid.

3. The subtropical high is stable and not very active.

4. The cold air activity in summer in China is generally in the north, and the south is not affected by polar airflow.