My grandmother who is now passed told me something about September predicting the weather. Can someone help me remember how it goes?

It was something about whatever the weather was on Sept 28th or Sept 29th would predict what the majority of the weather would be for the next 6 months. I can’t remember if it was the 28th or the 29th that it is based on.

If someone out there knows the specifics of this wise tale and if it is the 28th or the 29th, please let me know.