Been in Houston in the summer and live in South Florida, and your humidity does not impress...
Heat index is usually over 100 and the sun is far stronger.
I daily drive convertibles and have for the past 10 years. The 986 is just the nicest one so far. I would drive this car in any kind of heat. My AC is pretty effective even in stop and go traffic. I am usually doing 75mph on my commute and the AC is quite cold. I don't drive with the top down, unless the sun is down...
I am not sure I would daily this car in snow, but that's not my problem.
I don't understand why you can't enjoy your car year round. Do you stay indoors all summer? It's hot everywhere, so turn the AC up and if it's too hot for you, start the car and let it cool down while you stay inside in the AC.
