Autumnal equinox date 2025

Arab Weather - Astronomical calculations indicate that the autumnal equinox in the Northern Hemisphere this year falls on Monday, September 22, at 9:20 PM Mecca time. This is when the Earth's tilt aligns with its orbit around the sun, and the sun is directly overhead over the equator. Both the Northern and Southern Hemispheres receive the same amount of sunlight and the same hours of daylight and night.

What happens on the autumnal equinox?

On the autumnal equinox in all countries of the world, the sun rises in the true east, making a 90-degree angle with the horizon, and sets in the true west, at a 270-degree angle with the horizon, where the sun is perpendicular (in its apparent motion) to the equator.

After the autumnal equinox, the sun continues its apparent journey across the horizon towards the south in the Northern Hemisphere, until it reaches its farthest south on the winter solstice.

After the autumnal equinox in the Northern Hemisphere, night begins to gain increasing minutes of daylight each day for three months, until the winter solstice in December, which marks the longest night and shortest day of the entire year in the Northern Hemisphere. The opposite occurs in the Southern Hemisphere.

How does the weather change with the beginning of fall?

Arab Weather experts point out that changes in weather patterns in the Northern Hemisphere don't occur quickly with the onset of the autumnal equinox. The autumnal equinox occurs at a specific point in time and marks the official start of autumn in the Northern Hemisphere. However, its effects on the weather aren't immediate, but rather represent a turning point in the seasonal cycle.

Weather patterns will gradually respond to this shift over the coming weeks. After the equinox, the Northern Hemisphere begins to receive less solar energy each day as the sun's path lowers in the sky and daylight hours shorten. This decrease in heating occurs slowly, so temperatures drop over several weeks.

How is the autumnal equinox different from the rest of the year?

• Astronomically, autumn officially begins on the autumnal equinox, and this year it lasts 90 days until the winter solstice.
• On the autumnal equinox, the sun is perpendicular to the Earth's equator during its apparent journey across the horizon.
• Day and night are equal throughout the world on the day of the autumnal equinox.
• The autumnal equinox is an opportunity to determine directions accurately because the sun rises in true east (at a 90-degree angle with the horizon) and sets in true west (at a 270-degree angle with the horizon).
• The full moon that occurs near the autumnal equinox is called the Harvest Moon, because the moon's brightness allowed ancient farmers to harvest longer into the evening.
• The autumnal equinox does not necessarily mean the onset of cold weather or rapid changes in the weather.