If summer weather appears to have arrived in your area, that may be why. Extreme temperatures can "burn" — so to speak — your iPhone's battery pretty rapidly, especially if it's left out in the sun. Apple users may notice the same impact in frigid winter temperatures as well.
That's because your phone operates best at 62° to 72° F, according to Apple.
It's not going to dramatically impact your cell phone if you go slightly above or below those temperatures — but extreme heat can be particularly damaging.
"Low- or high-temperature conditions might cause the device to change its behavior to regulate its temperature," warns Apple, noting that it could shorten your battery life or even cause the device to shut down unexpectedly. Though it's worth noting your battery should return to its normal status once it's stored in more normal temperatures.
A device that is stored in temperatures 95° F or higher could face permanent damage.
"That is, your battery won’t power your device as long on a given charge," Apple explains on its website. "Charging the device in high ambient temperatures can damage it further."
Apple recommends never leaving your iPhone in your car — as the inside of a vehicle can heat up quickly — or in direct sunlight. To ensure your phone stays "healthy," it's also important to avoid using iOS apps while walking around in hot weather and never charge it in the heat.
"Using certain features in hot conditions or direct sunlight for an extended period of time, such as GPS tracking or navigation in a car, playing a graphics-intensive game, or using augmented-reality apps" could change your phone's behavior, Apple added.
If your phone does turn off or your battery rapidly declines, then it's important to turn the phone off, immediately store it in the shade (in your bag, pocket or under a towel) or take it indoors, where there's air conditioning. According to CNET, iPhone users can even briefly store it in the refrigerator for an instant cool-down, but they're advised not to leave it in the appliance long. The tech website also suggests removing any protective cover from your hot phone to expose it to cooler air.
Users who suspect their phone is permanently damaged should contact Apple Support or go to the nearest Apple store for assistance.
For more iPhone battery-saving tips click here.