Do Jack Russell get cold

If its cold outside you should put a doggy sweater on him, if its inside you could wrap him in a blanket.

I live in Canada where temperature drop near -30ºc in winter and my Jack Russel can't stand any kind of dog cloths. He walk 3 hours a day no matter the kind of weather. The only times I've seen him get cold is because I was not walking fast enough or I took time to speak with bystander. They stay warm because they are very active have a double coat would be the appropriate answer I guess.