What do you think is the basic experience of knowing the weather from the cloud? Why do you say "to accurately grasp the weather changes, you have to rely on the weather forecast"?

The weather is unpredictable. The ancients didn't have satellite cloud pictures, only looked at the clouds, and big changes could be identified.

At present, the weather forecast of a satellite cloud image is far more accurate than looking at the cloud according to the direction and wind direction of the cloud.

But whether you look at the clouds or the weather forecast, it is an estimate, in other words, a guess, which cannot be completely accurate.