In my limited ammount of time that I have hunted before, during, and after the rut I have noticed the same thing as you. I think the weather does has a good deal to do with it. IMO it changes with the ammount of moisture in the area. The more wide spread the moisture the less concentrated the elk are around known watering spots and the less competition from other bulls. The cows are also less concentrated which leads to less estrous in the air to exciet the bulls.



Here are two back to back years with very different ruts.

Two years ago the rut was getting into full swing opening day (last weekend in August) and continued all through September. It stayed strong the entire month of September then began to wind down. There were so many bulls bugeling I didn't know which way to go at times. It was very dry this year and I believe the elk were much more concentrated around watering areas, which is where we hunt, and this led a higher concentration of elk and ultimately a earlier and longer lasting rut because of the added competition and hot cows in the area.

Last year The rut really didn't get started until the last week of September and went through mid October. It never really did get going hard though. I had a hard time getting a rise out of anything until the last week of September. This year there was a good ammount of rain which I believe to have spread out the elk more and there was not as much competition from numerous bulls nor as many cows around to get the bulls as excited leading to a more "relaxed" rut.