I have Black Tubes...(on the Boat befor Wilk steps in!
) and in the pretty Hot weather we've had here this summer its not been an issue at all...and I keep em pretty well pumped up!..
I couldn't say with your climate it would be the same though as I don't know...Although most Warm water RIB's seem to be light in colour,I'm not sure if that is not more to do with local Fashion/Styleing ???
..One tip.. the wear patches I have fitted don't warm up at all compared to the rest of the Tubes...and the Girls seem to sit there when its hot.
I am a firm believer in U.V Protection for any colour Tubes,and its one of the best things to prolong their look, and life span.
If your Boat is going on a Mooring and,or out in the elements, I'd go Light..if its Trailered and put away...you MAY be Ok.
Even over here...all colours soon Fade if they are outside and not well looked after.
Good luck and let us see what you end up with