My cellphone gets very hot...,

[Silverobama]

Is it natural to say "My cellphone gets very hot during the summertime"? I think it has something to do with the battery but I don't know how to express this idea. Every summer when the temperature reaches 35 degree Celsius, my phone starts to become very hot.

 

[emsr2d2]

It's OK. I'd probably just say "in summer" rather than "during the summertime". As I'm a BrE speaker, I'd say "mobile [phone]", not "cellphone". Of course, in the UK, you can't automatically assume that the fact that it's summer means it's also hot!
Although it's most likely the battery that's overheating, I don't think you need to be specific. Most people have had the experience of their phone being very hot to the touch (and even getting an "overheating" warning on the screen) in very hot weather so they'll immediately know what you mean.

 

[Silverobama]

Although it's most likely the battery that's overheating, I don't think you need to be specific. Most people have had the experience of their phone being very hot to the touch (and even getting an "overheating" warning on the screen) in very hot weather so they'll immediately know what you mean.

Much appreciated!

I was thinking about how I can naturally express this idea in English. Are the following sentences better and more specific?

1) My phone starts overheating every summer when temperatures reach 30°C, probably because of the battery.
2) When it reaches 30 degrees outside, my phone battery gets insanely hot.

 

[emsr2d2]

#1 is more specific but it's definitely not better. It's too wordy and I'd go as far as to say unnaturally formal for such a trivial matter.
#2 is just as OK as your original in post #1.

There's no right/best way to say this. Any grammatical sentence that expresses that your phone gets very hot in temps of 30+ degrees will work.