Really depends on the dog. Many years ago when I was a kid, we had a short haired terrier/beagle mix in Michigan. He never seemed to be cold, would roll around in the snow, I never once saw him shiver. Now we have a poodle/bischon mix in Southern California, she has lots of hair, and can not tolerate the heat. She is good for no more than five minutes outside, once it gets into the high 80's 90's and above. So watch your dog, if she gets cold, put a jacket on her, and cut outside exposure time down. Cutting outside exposure time is also in order for a dog that can't tolerate heat, like ours, who is a huge air conditioning fan.