That will vary based on the individual dog, breed, type of coat, age of the dog, their health and even their diet.

Dogs with longer double coats and good levels of body fat are better at handle a wider extreme of temperatures both hot and cold, since their coat and fat levels act as an insulator, even in high temperatures that insulation helps to keep their core body temps cooler,

If you have a dog with low body fat and thin coat the weather extremes there can handle is much less than the group above. during the hurricanes in the southerns where many people lost power and could not run AC or were trapped in the long traffic tie ups ended up losing their greyhounds to the heat. If I am going to outdoor events with my greyhounds on hot summer days where I won't have indoor shelter for the dogs to cool down in then I have to carry bottles of water some frozen to either pour over them to cool them down or put beside them when they are laying down to help keep them from overheating, my american eskimo though she is older can tolerate the heat better than them and does not need the water soaking.

Dogs that are ill or hyperthyroid will have a harder time with temperature extremes.

As dogs age you will often see reduced ability to handle extremes in temps

Diet, for dogs that spend a fair bit of time out of doors, they will burn off fat faster, so should be fed a higher percentage of fat during cold weather, or fed slightly more,

Windchills and humidity can also be a determining factor on how longer the dog is comfortable outdoor

As for feet, it is not so much the cold and snow that causes a problem but salt. My dogs will get frozen feet at temps below -30 C can handle -10 not problem in the backyard, but walk them on the where is just below freezing where sidewalks and roads are salted and they are holding up the feet crying