Why Does My Phone Overheat Inside a Waterproof Case?

Why Does My Phone Overheat Inside a Waterproof Case?

Explainer · Phone cases

Your phone heats up from the sun and from its own work, and a sealed waterproof case holds that heat in. Shade, a lighter workload and a few minutes out of the case fix most of it.

Updated October 5, 20265 min readTroubleshooting

Person holding a smartphone outdoors in direct sunlight

A waterproof case isn't broken when your phone runs hot in it. It's doing its job, sealing the phone in, while sun, navigation, the camera or charging pile on more heat than the phone can get rid of.

What's happening

Heat comes in faster than it gets out

A phone has two heat sources on a beach or boat day. One is outside: sunlight landing on it. The other is inside: the processor, screen and battery working, which climbs with navigation, video, the camera and charging.

A phone gets rid of that heat through its body into the air around it. A sealed waterproof case or pouch wraps the body in another layer and cuts off moving air, so heat leaves more slowly. In shade with the screen off, that barely matters. In full sun with GPS running, it can tip the balance.

Two heat sources, one slower way out.

Manufacturer guidance

What the phone makers say

  • Apple says iPhone works best in ambient temperatures between 32° and 95°F. When it gets too hot, charging can slow or stop, the display can dim or go black, cellular signal can weaken, camera flash may be disabled and performance drops. If it gets hotter still, you'll see the alert "Temperature: iPhone needs to cool down."
  • Apple lists the situations to avoid: leaving the phone in a car on a hot day, leaving it in direct sunlight for an extended time, and using GPS, the camera or games for long stretches in hot conditions.
  • Samsung says a phone will continue to heat up if it is kept in sunlight, suggests removing the case "to give it more room to cool down", and notes that charging always increases the temperature.
  • Google says some warmth from heavy use is normal, and that a hot Pixel may reduce performance, slow charging and turn off the camera flash. It recommends keeping the phone out of direct sunlight and out of enclosed or poorly ventilated areas, and using cases made for your specific phone.

Sources: Apple Support, "If your iPhone or iPad gets too hot or too cold"; Samsung Support (Ireland), "How can I stop my phone from getting hot in the sun?"; Google Pixel Phone Help, "Help keep your Pixel phone from feeling too warm or hot."

Fix table

Fix it by heat source

Find the line that matches your day. Most hot-phone moments stack two or three of these at once.

Where the heat comes from What to change
Sun on the phoneFace-up on a towel, deck or dash Move it into shade between uses, or into a bag. Apple, Samsung and Google all say to keep it out of direct sun.
Source: Apple · Samsung · Google
The phone working hardNavigation, video, camera, games Close apps you aren't using and use navigation or the camera in shorter bursts.
Source: Samsung · Apple
Charging in the caseBattery pack in the pouch Unplug, or take the phone out of the case first. Apple says charging inside certain cases may generate excess heat.
Source: Apple · Samsung
No air around itSealed pouch, closed car, tight pocket Give it open air: take it out of the case for a few minutes somewhere shaded and dry, away from the water's edge.
Source: Samsung · Google

Organized by SKÖ from the Apple, Samsung and Google support pages cited in this guide. Each row names its source.

Before you head out

A cooler day for a cased phone

  • Start with the phone cool, not fresh off a charger
  • Plan a shady spot for it between uses: a bag, umbrella or under a seat
  • Download maps ahead so navigation runs for less time
  • Close apps you won't need
  • Leave the battery pack out of the pouch
  • Never leave it in a parked car or on a dashboard

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