Why is the weather forecast in Shenzhen never accurate?

The weather forecast can't be 100% accurate, because it's only a forecast and is influenced by many factors.

Weather forecast belongs to forecasting science. According to the laws of science, forecasting science cannot be completely accurate or always accurate. The current level of science and technology, especially the understanding of the whole atmosphere and even the whole climate system, determines that our weather forecast cannot be completely accurate, and there must be some contingency.