While I was in Louisiana last week the temp was in the mid 70's but the sun seemed really hot, so I tried reading in the sun, I managed to find an angle where I could sort of see the screen and managed to struggle through reading for about 10 minutes, I wanted to see if I could make my unit overheat but trying to see it while in the sun was not worth it, so I laid it on a towel on the trunk of my car, turned on in the book app. I let it sit there for over an hour and although it was very warm from the heat of the sun, it was still operating. I'm glad it did not overheat, but I still could not imagine trying to read while in the sun, so even if there had been a problem, it wouldn't have been one for me. I also thought I would set my Macbook Pro in the same environment, on the trunk with sun shining on the screen and keyboard. Within minutes the fan was on high even though there were no programs running at the time and the display was set to energy save (using integrated video). It did continue to operate but had almost killed my battery due to the high speed fan in less than an hour. I guess the heat of the sun may be an issue for many products, it is just more likely that someone would use an iPad in direct sun than many other products such as laptops.