Pugs are extremely sensitive to temperature both hot and cold. If your Pug gets to hot he or she could die. Never leave your Pug in a Car on a hot day (Pugs shouldn't be left in a car anyway for fear of Kidnapping!!!)
Pugs like to lay in the sun, you should limit the time they spend to just a few minutes.
Be careful not to exercise your Pug in hot weather, in the summer walk them either in the shade or at either end of the day when the sun is at it’s weakest.
Even if a Pug doesn't show signs of heat stroke, over heating can cause damage to organs such as the kidneys, Heart and liver.
If you do suspect your Pug has heatstroke, cover them in a cool damp towel, use a fan if you have one handy and give them plenty of access to water. Lastly get them to a vet.
Pugs also feel the cold due to the fact they are small and therefore have a small body mass and they only have one coat unlike most dogs that have two. If you are out and about in cold weather you Pug will greatly benefit from a warm coat, fleece or hoodie. If it is raining water proof clothing should be used, your Pug should also be dried off once you are back in the dry.