Why is the weather forecast in summer untrue?

In fact, most of the weather forecasts are accurate, but what he forecasts is cities or places, and the geographical area covered is too large. Although he is in the same city, different towns will have different weather. It doesn't rain where he is, and it is raining cats and dogs several kilometers away, even hundreds of meters away, especially in summer, which is dominated by showers, and in autumn and winter, it is mainly rainy, so the feeling of inaccurate weather forecast is very small.