How did Zhuge Liang know the weather?

Because the development of astronomy now lets us know that astrology is regular and accurate. For example, the ancients thought that "the old star is the head" is the astrology that is beneficial to the king. But now we know that the so-called "year star" is actually Jupiter rushing to the sun. Once a year. And it can be accurate to one thousandth of a second. What's the mystery? Don't look at the sky. Many astronomical websites have forecasts of various astronomical phenomena every year.

However, the ancients did not distinguish between astronomy and meteorology. These are astronomical figures. So sometimes the weather is predictable, which has scientific basis. Just like the weather forecast now. For example, it is entirely possible for Zhuge Liang to know that Jiazi will be easterly and foggy at night.

As for fortune tellers, they are sometimes accurate. There are some famous tricks in the Jianghu. What he says is often a bit ambiguous at first, and then further confirmed by observing the words or himself.