Okay; so this is neither the first, nor real autumn foliar color. It just happened to be convenient for me to get a picture of. Someone left this unfortunate Japanese maple right outside on the driveway a few years ago. It colors early from uncomfortable exposure to late summer warmth. The picture below is even more colorful, and was from even earlier in the year, last August.
Foliage that is starting to color here is nothing to brag about. Some of the older dogwoods leaves just shrivel and turn brown. I can only hope that enough newer foliage lingers to color as well as it did last year. Cottonwoods start to drop foliage while it is still green, but should eventually color to a subdued yellow before the last foliage falls. Sycamores are bland no matter how late.
There are only a few trees that reliably develop vibrant foliar color in such mild autumn weather, and only a few of such trees happen to be in our landscapes here. We lack Chinese pistache, flowering pear and ginkgo. The few sweetgum that are scattered about provide most of the foliar color here in autumn. It is still too early for them to color though. They need a bit more chill.
Flowering cherry and dogwood, which are uncommon just a short distance farther inland, happen do do quite well for us, and mostly color remarkably well in autumn. They only need a bit more time and chill. Birches are not as colorful, but are bigger and bolder, and eventually cover the ground below with delightfully yellow foliage. Boston ivy was added only earlier this year.
Native flora does not contribute much color. Bigleaf maple turns only a soft yellow. Poison oak turns rich deep red, but there is not much of it.