Traveling by plane to a cold climate

I have seen travelers in warm climates and warm airports struggling with coats, carrying coats and wearing coats and then being uncomfortable.
Changing climates while you travel can bring up and number of issues. Here are a few ideas I have come up with:

1.) When traveling to a cold climate you are going to need a coat. But that does not mean that you have to wear the coat through security, around the airport or on the flight. If you have a lot of items that need to be taken out of your luggage at the security checkpoint your coat is going to be one more thing to wrestle with at this very uncomfortable time. Most airports are kept fairly warm during the winter; your coat is going to be a burden. Solution: Bring a coat that can be easily folded and stored in an external compartment in a carry-on bag (for a business traveler all bags are usually carry-on) Of course, if you are going to extremely cold climates the coat will be too large to stow in a carry-on. For most colder climates a medium coat with layers of clothing underneath will be more than adequate.
Have the coat packed in an outside compartment of your carry-on until you actually get into cold weather then pull it out and wear it.
2.) A change of clothes is usually for one day, so dress for the climate where you are going to be spending the most of the day/night. Example: If you have to make a quick dash to the airport in your home climate (warm) but are going to be exploring at your destination (cold climate) it makes sense to have on at least basic clothes for a cold climate (enough clothing to keep most of your body warm).
3.) If you are going to be on a long flight, wear the clothes that you are going to make you comfortable on the flight regardless of your destination climate (you can change when you get to your destination). If you are on a flight overseas, you are going to have to do everything you have to do to make yourself comfortable. If you have ever been on one of these flights you know what I mean. Even in first or business class, you are going to have to get comfortable for an extended period of time.

Final Note: It is my understanding that riding in a plane increases your risk of catching airborne illnesses. Do everything you can to prevent your body from being exposed favorable conditions for incubating an illness.