Races as workouts.
As we've said before, September through October is packed with race opportunities. Just check the SFTC Calendar and you'll see what I mean. Pick some interesting races and use them as weekend workouts.

Have fun with your running.
With so many races to choose from, you can shift your focus away from "building" and more toward "maintaining and enjoying". It's a great time to throw some variety into your workouts. Unless it's part a specific goal, don't try to increase your mileage. Instead, find new places to run and experiment with shorter distances at a faster pace, with brief rests in between. For example, you might run 1/3 of your typical race distance but at a quicker pace. Then rest 3 minutes and do it again. Or you can alternate fast & slow intervals into a normal jog. Maybe 2 minutes fast and 2 minutes slow... over and over. And of course be sure to enjoy the fall colors and smells in nearby parks or neighborhoods.

Good Times, Great Runs.
Don't be surprised if it feels easier to run during the fall. The low humidity and mild temperatures allow your body to exercise much more efficiently. ENJOY IT!