Ganesh Chaturthi's connection with rainfall

Have you ever noticed that at most places every year on Ganesh Chathurthi, rainfall may be scantly but occurs? Why is it so? Is there any relationship between Ganesh Chathurthi and rainfall?

The beginnings of the Ganesh festival can be traced back to a time when most of the populace of India lived by a source of water, usually rivers. According to the Indian calendar, towards the end of the month of Jhyestha, when the constellation of Mriganakshatra is sighted, we begin to see the first signs of the rains. This is when a series of festivals respecting the Earth begin. So, obviously Ganesh Chathurthi that is celebrated in the monsoon will have chances of occurrence of rainfall on that day. Yet, this reason is not convincing for there are many cases wherein there is a recorded meteorological drought but rainfall happens on Vinayaka Chavithi.

If we have a deep insight into the statistical record, let it be a drought like situation or otherwise, certainly, on Ganesh Chathurthi rainfall occurred in either Telugu state. Though there is no arguable reason for the same, yet people believe that surely there is a mysterious relationship between the two. Is it not evidence that God exists?