An easy way to check the temperature outside, no batteries required. Just stick the thermometer to any window on the outside surface and then go into the comfort of your own to view the outside temperature.
Tip: clean the window with warm, soapy water before affixing the thermometer. If the thermometer suction cup is warped or curled, simply use some warm water to flatten it out. This thermometer works best when positioned away from direct sunlight.