When does autumn start?

Spring 2025 was the warmest on record, but what will that mean for wildlife this autumn? Is autumn starting earlier or later than it used to? Please help us to answer these questions by tracking the timings of nature near you.

From birds migrating and fungi appearing, to fruit ripening and leaves tinting – we want to know when events like these happen across the UK! Watch the video below to learn more about recording the seasons with Nature's Calendar.

You'll be contributing to a long biological record that dates back as far as 1736, but we need to know what is going on now, in your local area.

When does autumn start?

Nature's Calendar autumn

At Nature's Calendar, our records are split into just two seasons: spring and autumn. Therefore, you may be recording 'spring' events like the first flowering hazel in winter, or recording 'autumn' events like the first ripe bramble fruit in summer.

We split our records into these two seasons purely for data management reasons. In Nature's Calendar terms, 'autumn' starts on the first of July!

In the wider context, there are two separate dates which could be said to mark the start of autumn in our calendars. An article from the Met Office explains that one is defined by the Earth's axis and orbit around the Sun and the second is a fixed date which is used by meteorologists for consistent spacing and lengths of the seasons.

Astronomical autumn

The astronomical autumn is defined by the Earth's axis and orbit around the Sun. The astronomical calendar determines the seasons due to the 23.5 degrees of tilt of the Earth's rotational axis in relation to its orbit around the Sun. This year, astronomical autumn begins on 22 September 2025 and ends on 21 December 2025.

Meteorological autumn

Meteorological seasons are derived by splitting the year into four periods made up of three months each. These seasons are split to coincide with our Gregorian calendar, making it easier for meteorological observing and forecasting to compare seasonal and monthly statistics. By the meteorological calendar, the first day of autumn is always 1 September; ending on 30 November.

The seasons are defined as spring (March, April, May), summer (June, July, August), autumn (September, October, November) and winter (December, January, February).

Reference: Met Office - When does autumn start

What might we see this year?  

Early indications suggest that this autumn will see an earlier than baseline average ripe fruit date for bramble across the UK. In fact, it may even be the earliest average date we have on record. Once we have received and digitised all our data, we’ll be able to calculate the UK average – so watch this space.

The bramble fruits may be early this year due to a number of reasons, including the higher-than-average sunshine levels.

Also, anecdotally, there have been several tree species displaying yellowing leaves as early as August this year, prompting several media outlets to question whether this year is a ‘false autumn’, like the one we had in 2022. In 2022, it was extreme heat and drought that was thought to be the cause of the early leaf yellowing and leaf fall. Trees would have been in a state of stress and entered into dormancy, dropping their leaves in response. On the other hand, milder autumns can also lead to longer growing times and later leaf fall. So, what might be happening across the UK this year? Again, watch this space to see what the data shows at the end of the season!