I really feel it has a lot to do with acclimation and what the dog is used to. It's the same with people really. 35-40 degrees would feel awful cold to someone who was used to deep south temperatures, but it feels like a balmy day to me in the winter. Tommy and Tasha live in the house, if they go out and it is -10 F or colder they pick up their feet and Tasha trembles and they want to come in quickly. But if they were outside all the time they'd be more acclimated and handle it easier, at least Tommy would, not so sure about Tash . I think Zero will be fine in about any weather you'd have though, Akitas generally have thick wooly coats and enjoy the cool weather .

As others have mentioned, I'd worry more about heat in the summer. Overheating is definitely more of a risk for him than getting too cold.