Maybe this scenario has happened to you:You leave your iPhone in your car or sitting in the sun. When you go to use it, a high temperature warning informs you that your iPhone needs to cool down before you can use it. If your iPhone is running too hot, stashing it in the refrigerator or freezer would quickly bring it back to safe operating temperatures. This means you should never leave any of your lithium-ion devices in the car in even moderately hot weather. Similarly, if your phone feels like it's running hot, avoid charging it until it cools down.