Why is the temperature difference between Yangzhou and Nanjing so great?

The reason for the large temperature difference between Yangzhou and Nanjing is that Nanjing is located in the valley along the Yangtze River, with low altitude, and the ground temperature and heat are not easy to dissipate. Air flows into the valley from the high terrain, and it cannot form clouds and rain, and the temperature is getting higher and higher. Yangzhou is located in the Jianghuai area, where the high pressure temperature is controlled after the plum rain, which makes the low-level airflow move to form dry weather in summer, and the surface temperature is less, so the temperature difference between the two is very large.