The autumn equinox is set to take place on September 22, marking the official start of the season in the northern hemisphere
12:48, 01 Sep 2025Updated 12:57, 01 Sep 2025
The autumn equinox is on September 22 this year(Image: Getty Images/Westend61)
As temperatures drop and foliage begins to shift to golden hues, it’s clear that the warmer months are drawing to an end. With that comes the much-anticipated autumn equinox, set to arrive on September 22 at approximately 7.20 pm BST. And dark nights are also coming, with the Sun setting for the first time in the second half of the year before 5 pm on October 26, 2025 in Glasgow.
This evening milestone will formally mark autumn’s arrival in the northern hemisphere, with daylight and darkness becoming nearly balanced in duration. “The Earth is tilted on its axis,” experts at Royal Museums Greenwich explain.
“This means that the Sun illuminates the northern or southern hemisphere more, depending on where the Earth is along its orbit. However, at two points in the year, the Sun will illuminate the northern and southern hemispheres equally. These are known as the equinoxes.”
As the observatory notes, our seasonal cycle primarily stems from how Earth moves in relation to the Sun. Equinoxes herald the arrival of spring and autumn, happening when solar rays reach both hemispheres equally.
The autumn equinox marks the official start of autumn(Image: ANP/AFP via Getty Images)
In contrast, solstices occur when Earth’s axial tilt peaks either towards or away from the Sun, ushering in summer and winter, respectively. Ancient civilisations skilled in natural observation are believed to have identified these cycles centuries ago.
They noticed these shifts whilst relying on solar positioning for timekeeping, forming the foundation of our seasonal knowledge today. According to the Met Office, this year’s ‘astronomical autumn’ will last roughly three months, concluding on Sunday, December 21.
An update issued on August 26 explained: “The autumn equinox signals the point when the northern hemisphere begins to tilt away from the Sun, leading to shorter days and cooler temperatures. From this point, nights become longer than days until the winter solstice.”
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It later added: “The season often brings unsettled weather, especially later on, when Atlantic depressions can lead to stormy conditions and strong gales. These changes are part of the natural shift as the country prepares for winter.”
The clocks are also due to fall back one hour at 2 am on the final Sunday of October, which is October 26. This will put the UK back on Greenwich Mean Time (GMT), meaning days will feel shorter and nights longer – though you might get an extra hour’s sleep.
Experts at Royal Museums Greenwich further explain: “Daylight saving, or summer time, is a mechanism to make the most of increased summer daylight hours in the northern hemisphere.
Computers and phones with an internet connection should automatically register any clock changes(Image: Getty Images)
“…A campaign at the beginning of the 20th century successfully argued in favour of changing the clocks during the summer months to avoid wasting time in the morning.”
Today, supporters contend that altering the clocks helps cut energy usage, promotes outdoor pursuits, and even reduces traffic collisions. Yet, critics argue that darker mornings could pose safety risks or cause ‘inconvenience’ to certain workers.
The experts add: “It’s an ongoing debate that strongly depends on people’s geographical location, occupation and lifestyle.” The UK will stick to GMT until 29 March 2026. At 1 am on this day, the clocks will spring forward to BST.
Computers and phones with an internet connection should automatically adjust to this change. But if you fancy jotting it down in your diary, the Government provides a comprehensive list of future clock changes on its website.
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