Select an outdoor clock for its features as well as its appearance. Any decent outdoor clock should be waterproof and it should have hardy features against other extreme weather conditions (such as thick glass in case high winds lash debris against the face of the clock). Your clock can also have other features, such a built-in thermometer and humidity indicator.
Select a location for your outdoor clock. You should hang it in an area where you can easily view it but where it has some shielding from the elements. For example, if the sunlight shines directly onto the clock, the colors may fade.
Install a metal hook into the vinyl siding of the house. If you do not have vinyl siding, you can also use a heavy-duty adhesive hook (as long as it goes directly onto a flat surface).
Lift the clock up to the hook. Outdoor clocks might be especially heavy, so you may need a friend to help you lift. Move it around until the back of the clock catches on the hook and sits evenly.
Let the weight of the clock rest on the hook but do not move your hands away until you are sure it will sit securely. Prepare yourself to catch it if it begins to fall.