Rarely! Flying with Dogs in Cargo, they are in a climate-controlled space.  The pilot’s manifest (list of who is on the plane) monitors and has control of the temperature in Cargo.
Your Dog will not be colder or hotter than the In- Cabin temperature. Also, airlines implement temperature embargoes and when there are extreme temperatures at the airport, you will be notified and may have to change your flight departure.
The airline will not board a pet if the temperature at the origin or destination is too hot or too cold. These embargoes are in place for the safety of your pet.See All About Extreme Temperatures at Airports and Flying with Dogs HERE