When is the first day of autumn? The official dates of the UK seasons explained

AS the summer heat fades, darker nights draw in, and the crisp morning air takes over, Brits may find themselves reaching for their favourite jumpers. But as the leaves turn brown and pumpkin spice returns to coffee shops, pinpointing the exact start of autumn isn’t as straightforward as checking the calendar. Depending on who you ask, autumn has either already arrived in the UK – or it’s three weeks away Credit: Getty Weather forecasters have one fixed date locked in for the ‘official’ start on autumn, while astronomers prefer to follow the movement of the planet Credit: Alamy Depending on who you talk to, you’re likely to get two entirely different answers to the question, “When is the first day of autumn?” Weather forecasters have one fixed date locked in, while astronomers prefer to follow the movement of planet Earth. Sign up for The Sun newsletter Thank you! What is meteorological autumn? Meteorologists divide the calendar year into four equal periods of three months each. These seasons are fixed according to our modern calendar, making it easier for climate scientists and organisations like the Met Office to track, record, and compare weather patterns from year to year. Under this system, autumn always spans the exact three-month period covering September, October, and November. That means meteorological autumn starts on September 1 and runs through until November 30, before winter “officially” takes over on December 1. Because it splits the year into four even quarters, weather experts can easily spot whether a particular summer was hotter than average or if an autumn brought unusually heavy rainfall. What is astronomical autumn? If you prefer to follow the solar system, autumn arrives a little later in the month. Most read in The Sun Astronomical seasons are defined by the position of the Earth’s orbit relative to the sun, taking into account key events like equinoxes and solstices. The word equinox comes from the Latin for “equal night”, marking the exact moment the sun passes directly over the equator. On this day, day and night are roughly equal in length everywhere across the globe. Because the Earth takes roughly 365.24 days to complete a full orbit around the sun, the precise timing of the autumnal equinox shifts slightly every year. In 2026, astronomical autumn officially begins on Wednesday, September 23, and ends on December 21, which marks the winter solstice, the shortest day of the year. The ‘official’ dates of the UK seasons To keep track of where we are in the calendar year, here is how the two official systems compare across all four seasons. SeasonMeteorological DatesAstronomical Dates (2026)SpringMarch 1 – May 31March 20 – June 20SummerJune 1 – August 31June 21 – September 22AutumnSeptember 1 – November 30September 23 – December 21WinterDecember 1 – February 28/29December 21 – March 19 Why do we have seasons? We owe our seasonal shifts to a 23.5-degree tilt in the Earth’s rotational axis. As our planet orbits the sun over 12 months, different parts of the globe lean toward or away from solar radiation. During peak UK summer, the Northern Hemisphere tilts directly toward the sun, giving us long, bright days. As we transition into autumn, our half of the planet begins to tilt away, leading to shrinking daylight hours, cooler breezes, and autumn rain. Comment now