Cool! That long, hot summer gives way to autumn at last as Met Office warns it's 'turning colder for all'

After almost four months and a record–breaking summer including five heatwaves, the next couple of days may see the last warm weather of the year.

Every day since June 11, temperatures of at least 20C have been recorded at least somewhere in Britain.

The Meteorological Office said this week will be 'feeling warm initially but turning colder for all'.

After early fog, warm sunshine is likely to be widespread on Monday, when temperatures could again reach the low 20s in England and parts of Wales, with highs of 23C (73F) in the South.

London is set to reach 21C (70F) on Tuesday, too. But, from Wednesday onwards, daytime highs are then expected to fall into the mid–teens Celsius – more common for the time of year.

The change will arrive after a band of rain moves south through Tuesday into Wednesday.

The Met Office said the rain could be 'potentially heavy for a time in the southeast'.

Dry and bright weather is set to return 'for most places' on Thursday but it will feel cooler.

A red deer stag at sunrise during the annual rut on Sunday in Richmond Park, London

Into next weekend, forecasters say it 'will be a changeable period as weather systems move in from the Atlantic, bringing spells of rain or showers to most areas'.

The cooler weather comes after the fourth warmest September since records began in 1884, according to provisional figures from the Met Office.

Even at the very end of the month, a warm spell brought temperatures of up to 28.1C (82.5F) at Kew Gardens, west London, last Tuesday.

Last month's mean temperature was 14.6C – but rainfall amounts were close to average after the long, dry summer which was the warmest on record.

The summer heatwaves are still having an effect – as the cider makers revealed they are set to have the worst harvest since their records began in 1984.

The poor crop is down to the dry conditions 'stressing out' the apple trees, growers say.

At Burrow Hill Cider in Kingsbury Episcopi, Somerset, where cider has been produced for over 300 years from its 200 acres of orchards, the crop is down about 50 per cent on last year.

The 'extremely long and hot summer and lack of rainfall has meant the apples have ripened prematurely, are smaller than usual and have dropped to the ground by the stressed trees', the company says.

Meanwhile, the effects of a hot, dry summer could see a vibrant but unpredictable display of autumn colour along with some plants flowering out of season, the National Trust has said.

Despite signs of a 'false autumn', in which drought–stressed tree leaves have turned brown and dropped early, the ingredients are still there for a colourful season – particularly if the coming weeks bring cooler, settled weather.

The summer sunshine should produce strong colour in the healthy foliage that remains but it is likely to be more varied than usual, the trust adds.

Some plants have responded to recent rain with fresh growth or a second flowering out of season – meaning there could be spots where maples are in autumn colour alongside rhododendrons in bloom.

Luke Barley, senior national specialist in trees and woodland at the National Trust, said: 'Autumn colour always depends on a combination of factors, but after such an extraordinary summer the usual signals are much harder to read.'

Trees may be more vulnerable than usual to high winds, the trust fears, as they may have to face wet, stormier weather brought by the current super–strength El Nino whilst holding onto their leaves amid milder conditions.

The arrival of autumn also looks set to vary significantly from place to place, too, the National Trust said.

Gardeners at Cotehele in Cornwall are expecting it three to four weeks later than usual, as its North American ash – one of the first trees to turn, sometimes as early as August – only began showing hints of its pink–purple colour in the third week of September.

But one of the key signs of autumn – the conker – may be in short supply as drought has led to a less abundant, noticeably smaller, crop at its estates, the trust said.