Last week, Apple revised a support document about iPhone temperature to include the iPhone 3GS. The June 25 document cautions iPhone 3G and iPhone 3GS users to operate their handsets within acceptable temperatures. It makes the following recommendations:
Recommended operating temperatures Operate iPhone 3G and iPhone 3GS in a place where the temperature is between zero and 35 degrees Celsius (32 to 95 degrees Fahrenheit). Low or high-temperature conditions might temporarily shorten battery life or cause the device to temporarily stop working properly.
Recommended storage temperatures Store iPhone 3G and iPhone 3GS in a place where the temperature is between -20 and 45 degrees Celsius (-4 to 113 degrees Fahrenheit). Don't leave the device in your car, because temperatures in parked cars can exceed this range.
Symptoms of overheating
iPhone will no longer charge iPhone display will dim Weaker cell signal iPhone temperature warning screen appears (see below)… Read more