'Thermometer in phone' is a precise tool for measuring temperature around you. It shows accurate temperature in Celsius and Fahrenheit degrees. It is the best way to check how hot it is in your house. Just open the app and check the results!
Some phones (like Samsung Galaxy S4) has special sensors for checking ambient temperature around the phone. This way you can easily check temperature in your room. If your phone does not support such measurement - app will use battery temperature and calculate more or less current temp. To get the most accurate results - leave your phone without using it for a few seconds before opening thermometer.