Diurnal temperature is the range of the Earth's temperature from low to high during one day. The lowest and highest temperatures during a 24-hour period are recorded for comparison and generally vary between 20 and 30 degrees Fahrenheit.
As the sun rises it heats the Earth. The ground first stores heat before radiating it and therefore contributes to the atmospheric temperature even after the sun has moved past its zenith. Once the maximum daily temperature is reached, the temperature begins to drop, generally reaching a low at some point during the night. Cloud cover, elevation, humidity, wind and geographic location can all affect diurnal temperature.