The temperature has dropped, days are getting shorter and the leaves are changing colour - it can only mean thing: autumn has arrived.
Marked by a cheery Google Doodle animation of a mouse sipping tea, the new season promises woodland walks, conker fights, pumpkin lattes and lots of cosy evenings in.
But what makes today the first day of autumn - and how is it connected to the equinox?
When is the first day of autumn?
There are two options to chose from - and it depends whether you follow the meteorological or astronomical calendar. There's three weeks difference between them both.
Meteorological calendar - September 1
In meteorological terms autumn begins today, on September 1, and ends on November 30. The meteorological calendar uses our Gregorian calendar to split up the four seasons into three month blocks, which, according to the Met Office, makes it easier to observe forecasting and compare seasonal statistics.
- Spring: March, April, May
- Summer: June, July, August
- Autumn: September, October, November
- Winter: December, January, February
Astronomical calendar - September 22
Astronomers base the date of the seasons upon celestial events, in autumn's case the autumnal equinox, when night and day are roughly equal length. In 2017 this takes place today, on September 22.
The equinox happens when the equator passes the centre of the sun. This is when the north and south poles of the Earth are not tilted towards or away from the sun, as at other times, but are aligned so as to give, theoretically, the same amount of daylight in both of the Earth's hemispheres.
There's a third definition....
The third definition of the start of autumn, which is more fluid, comes from phenology – the study of periodic plant and animal life cycle events.
The start of autumn in this field is dictated not by a set date or a single event, but the changes in the natural world, such as the tinting of the trees and the ripening of autumn fruits.
For some the first blackberry, which can ripen in July, heralds autumn, while for others it has arrived when the trees are bare, which can occur in December.
What sort of autumn can we expect this year?
Experts from the Forestry Commission say soggy weather over the summer is likely to give way to colourful and lengthy autumn.
The warm, dry spring could have prevented the sugars forming in trees which create the rich hues in their leaves. But the wet summer weather has helped trees to catch up, say experts, and it should result in a stunning display, even if it comes slightly later than normal.
Maple species are expected to kick off this year’s show, with beeches and oaks giving the nation a ‘second autumn’ later into November.
Experts are also anticipating a crescendo of colour which will come around the last two weeks in October, although it is dependent on heavy rains and wind staying away.
Why do leaves change colour?
They stop producing chlorophyll - which gives them their green colour - at the end of summer, allowing other pigments, from yellow to red, to come through. Dry weather leads to more sugar in the leaves, which in turn increases the amount of anthocyanins that make leaves red.
Which trees show the most colour?
Maple leaves blaze red, also worth watching are oak, hickory, ash and beech.
When do the clocks go back?
British Summer Time will come to an end on Sunday, October 29 when the clocks go back one hour at 2am and GMT resumes - meaning another hour in bed for Britain.