When did Baoding start to cool down?

The weather began to get cold after beginning of autumn in Baoding.

After Baoding beginning of autumn, the weather will gradually turn cold. There is a folk proverb; Beginning of autumn, throw away the fan. Even if the sun is shining, you will still feel hot, but you will feel cool as soon as you get to the shade, especially at night. This is because the irradiation angle of the sun on the northern hemisphere of the earth has changed, which is formed by the revolution of the earth around the sun.