Autumn in Oman to begin on September 23; temperatures set to fall 

Oman to Witness Autumn Equinox on September 23 at 4:05 am

Muscat: The autumn equinox will occur in the Sultanate of Oman tomorrow, Wednesday, marking the astronomical beginning of autumn in the Northern Hemisphere and coinciding with the gradual retreat of monsoon winds and the decline of the climatic Khareef season in Dhofar Governorate.

Al Reem Hamad Al Malki, a member of the Oman Astronomical and Space Society, said in a statement to Oman News Agency (ONA) that astronomical calculations indicate that this year’s autumn equinox will occur at 4:05 am Oman time on Wednesday, September 23.

In Muscat Governorate, the sun will rise at 5:55 am, reach its highest point in the sky at 11:59 am, and set at 6:03 pm, resulting in a daylight period of approximately 12 hours and 7 minutes.

Al Malki explained that the slight difference between daylight and nighttime is due to atmospheric refraction, which causes the sun to appear above the horizon shortly before its actual sunrise and remain visible shortly after its actual sunset as its rays bend while passing through the atmosphere.

She noted that the exact equality between day and night, known as the equilux, will occur in Oman on Monday, September 28, 2026. On that day, the sun will rise at 5:57 am and set at 5:57 pm, giving a day length of exactly 12 hours.

With the autumn equinox, daylight hours in the Northern Hemisphere will gradually decrease while nighttime hours increase, continuing until the winter solstice, when the Northern Hemisphere experiences its shortest day and longest night of the year.

In the Southern Hemisphere, the opposite occurs as daylight hours begin to increase with the astronomical start of spring.

Al Malki explained that on the day of the equinox, the sun appears to move from the Northern Hemisphere to the Southern Hemisphere. Astronomically, autumn begins in the Northern Hemisphere while spring begins in the Southern Hemisphere.

With the beginning of autumn, the angle at which sunlight reaches the Northern Hemisphere gradually decreases, reducing the amount of solar energy received during the day.

She stressed, however, that the astronomical start of autumn does not mean an immediate or sudden decline in temperatures. Weather conditions are influenced by various climatic and atmospheric factors, including wind movement, air currents, air masses, heat and cold waves, and the geographical characteristics of different regions.

As a result, hot weather may continue in some areas even after the equinox has occurred.

Al Malki added that the autumn equinox, which generally occurs between September 22 and 23, is also associated with the sun rising almost precisely from the east and setting almost precisely in the west.

She noted that at the equator, shadows disappear at noon during the equinox in a phenomenon known as “Zero Shadow Day.”