There are many ways to predict the heavy rain at the funeral. There is a theory that rainy weather occurs because the old people in this world have accumulated blessings, and it is the old people who bring the blessings of the underworld to the dead for future generations to enjoy. Another way of saying this is that it rained during the funeral, which means that the old man did a lot of good deeds and accumulated a lot of good deeds before his death, so that his children and grandchildren can also enjoy the good news. There is also a saying that it rained during the funeral, indicating that God was crying, because the old man did a lot of good things to the deceased and touched God.
The above are some folk sayings, which have no scientific basis and cannot be used as a judgment standard.