All the leaves don’t turn colors and drop together.
My favorite tree is all green now, with just a few bright red splotches splattered around.
In the parking lot at work, a few dry leaves gather and blow, but the woods are still summer.
Change can be radical, but may not happen all at once.
You get a little warning, time to prepare and adjust. For awhile you can do summer and fall at the same time, but it has to be done knowing the change is coming.
This is your warning. Whatever it is, start now.