Having been to Hawaii and lived on Okinawa for two years I can tell you that on tropical islands in the Pacific the weather is very random and likes to turn the rain on and off at completely random moments so that's a legit reason.

 

Does it start monsoon pouring rain out of nowhere on a perfect sunny day? When I was there it did rain a few times even when it was sunny out. But it was mere sprinkles. It was like the 'April Showers' we have here in the North East on the mainland.

Even if it was real rain, if you aren't on the highway, you pull over, 6 seconds later your top is up. If you are on the highway, you don't worry about it since as long as you are moving you won't get wet.

Not seeing how threat of rain on a sunny day is a deterrent to top down.

 

A lot of people dont put the tops down on convertibles. Sometimes it's they do not want to mess up their hair. Othertimes, I think people are just lazy - esp if its not a power top. As for the windows up with top down, this adds the benefits of reduced noise, increased heat/ac, and your passenger's hair can survive better if thats an issue. I like to put the windows up on the highway if I am driving a long distance.

And i drove to work today with the top down in a drizzle. Almost pulled under a bridge but made it the whole way!

 

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