Davjos, I'm in Austin and last August installed a three year old 42" Philips plasma to a covered cabana down by the water. I checked the operating specs for the plasma, high end was almost 105 degrees, low end 35 degrees, max humidity of 90%. Keep in mind that's operating limits, non-operating I'm sure are probably much broader and I didn't think I'd be outside watching TV at any of those operating extremes.
This cabana has a fireplace as well, and although I considered mounting the plasma above it, I decided not to because of possible heat and smoke issues. Outdoor fireplaces behave much differently than indoor ones.
So far it's survived nicely. The Philips Ambilight feature is especially cool outdoors. The only thing I've been thinking of is having a Sunbrella cover made to keep dust and mud-daubers out.
I say go for it.