Don’t Charge Your iPhone in Extreme Temperatures
Charging your iPhone in extreme temperatures can be detrimental to your battery. Extreme heat and/or cold are not your friends when it comes to battery preservation.
Apple recommends charging your iPhone (as well as other Apple devices) when the temperature is between 0º and 35º C (32º to 95º F). If the temperature is too cold, your iPhone will stop charging until the temperature goes back to normal.
Similarly, if it’s too hot, your iPhone will shut off and notify you with an alert. Wait until the temperature drops to re-start charging your iPhone.