Diurnal may refer to:

• Diurnal animal, a plant or animal that is active in the daytime
• Diel, actions which are completed in 24 hours and are repeated every 24 hours; this can be seen in the diurnal temperature variation
• Diurnal motion, the apparent motion of stars around the Earth, caused by the Earth's rotation around its axis. More generally it means repeating daily as in e.g. diurnal effect
• Diurnal phase shift, the phase shift of electromagnetic signals associated with daily changes in the ionosphere

In astrology:

• Diurnal planet, a planet in a sect for which the Sun is above the horizon
• Diurnal chart, a chart for a given date, based on the natal chart
• Diurnal arc, the time, as expressed in right ascension, it takes a planet, point, or degree to move from its rising point to its setting point
• Diurnal sign, a sign in the zodiac whose natural positions are on the southern hemisphere of the horoscope

Diurnal