I try not to start rootings later than mid-September. About the only exception is when a branch is accidently broken off. Is grafting the same as rooting, better to do this in the spring/summer?

It is good to graft when the sap is free flowing and that usually stops around dormancy. In our area that occurs near Christmas or somewhat earlier. It will be fine to graft until then.

Good information. Thanks. We start getting some cool nights in October, and after a couple of weeks of nights in the mid to lower 60's (rather than mid to lower 70's), most of my plumeria begin to drop leaves. That's the reason I use September as my last month of rooting. Perhaps I can extend that end-point somewhat. Does the "grafting-season" extend longer than the "rooting-season"?

Based on the above information, you should be good to graft until mid-October.

Excellent. You have given me an extra month to get that done. Things will be slowing down (as far as Tropical Plants & More shipping), so I have more time to do things like grafting then.