Hi Tony, and welcome. I'm in Florida so a little more similar climate to yours here. I very seldom can grow lavender through the summer here. It really hates the humidity and high heat, night and day. They do fine for me from fall through to spring when it is cooler and drier. But in summer they generally develop root rot from staying moist all the time in the humidity, and just give up. I've lived here 14 years and only once has a lavender made it through a summer. It died the next year.
As Sue suggested, it might do better indoors, if you are running a/c but you would need to let it grow in a sunny window because they need lots of sun. Most herbs from the Mediterranean region have similar needs - drier air, letting the roots dry a bit between waterings (use a coarse, well draining medium) and sun.
