First, let me compliment your website. Since I’ve moved to the South (I’m from California), I’ve seen some crazy bugs that are HUGE and your website has helped. This past summer we’ve moved from Louisiana to College Station, TX, and this spider was ready to welcome us on our apartment balcony. It was frighteningly huge. Is it the Golden Orb Weaving spider? It is a picture of the belly, I think. I didn’t have the heart (or nerves) to try and flip it over to get a picture to see the other side of it. Thanks!
Your spider is definitely one of the Orb-Weaving Argiopes, probably Argiope aurantia which sometimes goes by the common names Black and Yellow Argiope or Golden Orb Weaver, and occasionally Orange Orb-Weaver which gives some indication of the variability of the coloration and markings of individual specimens. They are distributed throughout the U.S. including California. They are truly impressive spiders.