When it's this cold you need to wear layers, stay indoors, limit a pets outdoor activity and turn the heat up really high. As we all know extreme cold weather can be very dangerous.
So what's a cell phone to do?
Well first of all, your phone needs to stay warm too. The ideal temp for most modern smartphones (iPhone, Galaxy S, Droid, Lumia, etc.) is between 32-95 degrees Fahrenheit. So when they get too cold they can not work so good.
In extreme cold your phones battery could just shut down - not to worry it should come back after it warms-up a bit. BUT don't just keep pushing the power button out in the cold because you could cause more harm.
Let the little fella warm-up before you try to power it on again. A nice gradual warm-up is best. In fact the best thing you can do in cold weather is keep the phone closer to your nice warm body - pants pocket is good. If you keep it at a nice temp range it's more likely going to handle the extreme cold.
Leaving your phone in a cold car is a REALLY bad idea (as is putting it on a grill, but I hope I didn't need to tell you that).
One of the biggest dangers you might encounter is a broken screen. You see in the extreme cold the glass will become more brittle and has a MUCH higher chance of breaking. It's especially susceptible to damage if it already has a small crack, chip or other defect in the glass. Once you have cracked the glass on a phone it is more likely to encounter other issues and become further damaged. SO get the Glass fixed if it is broken.
If your phone shows other issues in the extreme cold don't be surprised. Also, don't be surprised if some smartphones function better than others in the cold. Again, let it warm-up and see if things work better.
When faced with extreme cold simply stay inside with your your little bundle of joy and you'll avoid most harm. But if you do drop your phone on the fireplace hearth or it slips into your hot cocoa bring it into WiGoClinic - Cell Phone & Tablet Repair for fast & friendly service!
Stay Toasty My Friends!