Why does the weather forecast in Japan always say sunny?

When China broadcasts the weather forecast, it will say "Where there is a chance of heavy rain tomorrow"

Japan's broadcast will say "Where there is a possibility of heavy rain tomorrow" sometimes followed by A probability or something

It’s just a difference in the way of broadcasting, it doesn’t matter

This is a predetermined custom in China, because everyone knows that the weather is uncertain

So just Tell me the result

Japan just prefers to add those words "probably, maybe"

These are just customary

It's like foreigners buying a knife What else should be written on it, like "cannot be used to kill people"?