The Dew Point calculation displays when the temperature is 79°F (26°C) or below. There is no way to manually adjust the temperature reading so the dew point will always read. If your temperature is 80°F (27°C) or higher the heat index will show. If the temperature is 40°F (4°C) or lower then the wind chill will display on the display. When you calibrate the temperature you are only able to calibrate it +/-10 degrees.