4 Exposing Your iPhone to Extreme Temperature Changes
From extreme heat to chilling cold, it shouldn’t come as a surprise that temperature changes wear out your battery and the device. Hot temperatures may affect (or even destroy) your iPhone’s hardware, while colder temperatures may cause your device to (literally) freeze up.
This also means you should be cautious about bringing your phone into the bathroom while you’re showering, and never bring your iPhone into the sauna after your workout. Though seemingly harmless, these temperature shifts (plus the added moisture) can ruin your device in the long term.