Why does the weather forecast report the temperature from high to low?

The highest temperature in a day appears around 14: 00 after noon.

The highest and lowest temperatures in a day appear at dawn.

If the weather forecast is made that night, the temperature information generally refers to the period from 0:00 the next day to 23: 59 the next three days.

If the weather forecast is made at noon that day, the temperature information generally refers to the period from about 12: 00 on the same day to about 12:00 on the next day.

So: Why are there two ways to broadcast the temperature in CCTV weather forecast: (A: 18 degrees to 15 degrees) and (B: 15 degrees to 10 degrees)?