Autumn officially begins in the UAE on September 22

Abu Dhabi: Autumn in the UAE will begin this year on September 22 at exactly 10.20 pm, when day and night will be nearly equal in length worldwide. At this point, the sun begins to gradually tilt southward, signalling the start of a noticeable decline in temperatures across the Northern Hemisphere.

Speaking to Gulf News, Ibrahim Al Jarwan, Chairman of the Emirates Astronomy Society and member of the Arab Union for Astronomy and Space Sciences, explained that general climate data for autumn in the UAE shows a gradual cooling trend.

• At the start of the season, temperatures average 37°C during the day and 23°C at night.

• By mid-autumn (November 8), averages fall to 32°C by day and 18°C at night.

• At the end of the season (December 21), highs average 26°C and lows 14°C.

 He added that humidity remains relatively high in September and October, before gradually decreasing by mid-November. Average autumn rainfall is less than 2 mm in October, 5–6 mm in November, and 16–18 mm in December.

 Astronomical events in autumn

 Al Jarwan highlighted the variety of astronomical phenomena visible in autumn, some occurring annually at fixed times—such as bright stars and major meteor showers—while others vary in timing, including new moon phases, eclipses, and comet appearances.

He noted the new moon dates for the season:

• Rabi‘ Al-Akhir: September 21, 2025

• Jumada Al-Awwal: October 21, 2025

• Jumada Al-Thani: November 20, 2025

During these nights, the moonlight is faint, with limited duration in the night sky, enhancing opportunities to observe comets, stars, and distant galaxies.

Increase in meteor showers

Al Jarwan said several prominent meteor showers will peak in autumn:

• The Orionids, reaching maximum activity on October 21–22.

• The Taurids, active through November, often produce bright fireballs.

The best viewing times are after midnight, away from light pollution. He added that autumn evenings also feature the appearance of bright eastern constellations and stars, including the Summer Triangle (Vega in Lyra, Altair in Aquila, and Deneb in Cygnus), Orion (known to Arabs as “Al-Jawza”), Cassiopeia (“Al-Naqah”), Andromeda, and Pegasus (the “Autumn Square,” which Arabs once called “Al-Dalw”).

In the UAE, daylight duration will be about 12 hours 18 minutes at the start of autumn, 11 hours 30 minutes mid-season, and 10 hours 55 minutes by the end. There will be no lunar eclipses or solar eclipses visible during autumn 2025.

Autumn as a transitional season

According to Al Jarwan, autumn in the UAE marks the transition between the scorching heat of summer and the mild cold of winter, with temperatures dropping more sharply at night and in desert and mountain regions. The season is characterised by clear night skies—ideal for stargazing in dark, unpolluted areas.

Astronomical autumn officially begins when the sun is directly overhead the equator at the autumnal equinox, which this year occurs on Monday, September 22, 2025, at 22:20 UAE time.

Major astronomical highlights of autumn 2025

Al Jarwan concluded by noting that autumn skies may feature two visiting comets:

• Comet Lemmon (C/2025 A6) — which could be visible to the naked eye or with binoculars.

• Interstellar Comet 3I/ATLAS — originating from beyond the solar system, expected to be visible with binoculars or small telescopes.