It's interesting how a dog will react to cold weather if they haven't been introduced to it early on in their development. Using a coat on my dog in 30-40 F degree weather would be like plugging in my car at that same temperature….seems strange; just coming from the environment I come from. I wouldn't even put a coat on myself in that kind of weather unless I was outside for more than a couple hours... and dogs [horses] have way more efficient circulatory systems than humans.
I'm sure it's necessary for dogs who have health issues, older, not used to 'extreme' winters, or that spend most of their time outside in under 30 F weather. With that being said, I'm not very good with the cold so I rarely go outside long if it's under -8 F. Beo only has a red hooded sweater with a sherpa overlay coat, and water resistant insulated booties for under 20 degree weather. We haven't had a problem so far but no -50 weather for us either thanks.
Definitely some cute jackets in here!