Why is the weather forecast temperature in Jiading much lower than that in Shanghai?

Because of the urban heat island effect.

In cities, due to the hardening of roads, the increase of buildings, the relative scarcity of vegetation, and the heat dissipation of automobiles and air conditioners, these artificial structures absorb heat quickly and have small heat capacity. Under the same solar radiation conditions, they heat up faster than natural ground (green land, water surface, land, etc.). ), so their surface temperature is obviously higher than the natural ground. The absorption rate of sunlight on the urban surface is higher than that on the natural surface, which can absorb more solar radiation, thus making the air get more heat and the temperature rise. The temperature in the city is obviously higher than that in the outer suburbs, which is called urban heat island effect.

Generally speaking, the more people, the more buildings, the bigger the city, and the more obvious the heat island effect.