Thorpe wrote:
Sorry, I'm in southern Maryland, that's zone 7A.

OK, then I would say that you can plant clematis now. The main
consideration for fall planting is how soon (if ever) you will have a
killing frost, since that will stop growth on most winter-hardy plants.
You also want reasonably warm day-time temperatures, ie, 45-50 degrees F
or better. There should be enough time, a month or so, for the plant to
develop its root system, which means that the leaves must still do some
photosynthesis. Apply some bone meal or other high-phosphorus
fertiliser, too, and water enough to keep the spoil moist but not
sopping wet. Check whether your variety of clematis wants acid or basic
soil, and amend if necessary. NB that clematis should go through a
period of dormancy in the depth of winter.

HTH&GL