Why is the weather forecast sometimes inaccurate?

Weather forecast is a high probability event, not an absolute occurrence.

Weather forecast is to predict the weather conditions in a certain period in the future by applying the law of atmospheric change and according to the current and recent weather situation. It is based on the analysis of satellite cloud images and weather maps, combined with the comprehensive study of meteorological data, terrain and seasonal characteristics, and mass experience. For example, the satellite cloud image of China Central Meteorological Observatory was taken by Fengyun-1 meteorological satellite made in China. Using satellite cloud images for analysis can improve the accuracy of weather forecast. The time limit of weather forecast is usually divided into three types: short-term weather forecast (2 ~ 3 days), medium-term weather forecast (4 ~ 9 days) and long-term weather forecast (10 ~ 15 days or more). CCTV mainly broadcasts short-term weather forecast every day.