African/Southern African-American Proverb
When you die the same season or month you were born, your time on this earth is coming to an end at the right time, if and when you die at any other time it is usually an untimely death.
The proverb or belief is used to explain or justify death, something that remains mysterious and inexplicable to people. My informant first heard this saying from her grandmother after her own father died at age 50. They considered his death untimely because he was so young and seemingly healthy but had a sudden and lethal heart attack. He was born in September and died in February so that strengthened their belief that his passing was an untimely one.
My informants mixed race family is from New Orleans, LA and she said her grandmother had lots of wisdom that she traced back to African although to her it seemed especially endemic to Louisiana. People often use sayings to justify or explain an occurrence that they have no control over and this saying is an example of that.