It does. There are a lot of things that can't handle too much cold or heat. Where is Montgomery? Most of Texas is 7 or 8 unless you're way north or right along the coast. If you want to see for sure, Google USDA Plant Hardiness map. Also remember that when things say they can take full sun, they don't always mean Texas sun.
I checked, your 8b. That means the warmer half of zone 8. Things like plumbago and purple fountain grass are perennials for you, but annuals for me. It also means that you an probably gorw things like lettuce and spinach all winter long, I can't. Hope that helps.