I live in Georgia, and would recommend a 16 oz without hesitation. The heavier wool holds pleats better, is more manageable, wrinkles less in the humidity, is more durable, etc.

It's not really the weight of the wool that creates a feeling of unpleasant warmth in the body as much as it is whether the hose or socks that you are wearing hold body heat or release it. Ask a woman about wearing knee highs. Or talk to people who play in a pipe band.