Titled "Keeping iPhone 3G and iPhone 3GS within acceptable operating temperatures", Apple provides some common sense approach to protecting your mobile investment
Essentially, you need to keep the iPhone from situations where it could really heat up. Direct sunlight or an environment with excess heat, like in a car. Truly, common sense.
Here is what folks need to keep in mind. The iPhone and other mobile devices like it are not really mobile phones. The iPhone is a mobile computing platform that happens to be able to make phone calls. Other than that you can do 95% of your daily Internet tasks, computing, and entertainment all on this excellently engineered mobile computer.
Apple provides two temperate ranges. One for operating and another for storage.
- Operate iPhone 3G and iPhone 3GS in a place where the temperature is between 0º and 35º C (32º to 95º F). Low- or high-temperature conditions might temporarily shorten battery life or cause the device to temporarily stop working properly.
- Store iPhone 3G and iPhone 3GS in a place where the temperature is between -20º and 45º C (-4º to 113º F). Don't leave the device in your car, because temperatures in parked cars can exceed this range.
Operating the iPhone outside of recommended parameters can affect battery life and iPhone functionalities. Discoloration of the case would be the least of your worries.