Just like you and me dogs can suffer from temperature extremes. Hyperthermia, hypothermia, dehydration and frost bite are the most serious and common illnesses caused by weather extremes. Keep in mind that every dog is different in their tolerances so don’t go by temperatures you find on the Internet. For example a small Chihuahua cannot withstand the cold like a Husky. The best method I’ve found to keep your dog safe is just a mix of observation and common sense. Often your dog will tell you what it wants. If you’re dog pulls towards home it’s a clear sign it doesn’t want to be outside. If you see your dog lift its paw or begin limping on a cold day it’s very likely that your dog has some salt in its paw or the ground is just too cold for comfort. Brush its paw gently and if it doesn’t immediately stop limping, head inside. In the heat of the summer just make sure you regularly fill your dog’s bowl with fresh water and that your dog has some shade. Finally, keep track of the time you’ve been outside with your dog and shorten it from your usual time outside on extreme weather days because dogs can get so excited about being outside, they will ignore their own state of health. Here are a couple of articles that provide some excellent detail on the subject.