They call it the heartbreaker grape – and for good reason.

“Pinot noir is so difficult to grow,” said Charlie Holland, chief winemaker at Gusbourne Estate in Ashford, Kent. “It’s very precocious. It needs to operate within a very thin band of conditions. If it’s too cold, you won’t get it ripe and it’ll be green and awful. If it’s too hot it turns jammy.”

Now, though, British winemakers are starting to believe that, after years of producing acclaimed sparkling and white wines, this year’s pinot noir harvest might create an outstanding red. “When you get a good year the wines are sensational,” Holland said. “They talk about a peacock tail of flavours – it’s the grape that is most complex, interesting and ethereal in style. It’s the holy grail for winemakers.”

Holland’s pinot noir grapes, unlike those used in his sparkling wines, were still on the vine last week: “We’re looking to hold our nerve for as long as possible. We’ve had an amazing growing season.”

Elsewhere, winemakers are celebrating this year’s harvest. “We’ve got some cracking reds,” said Duncan Schwab, head winemaker at Sharpham Vineyard, on the banks of the River Dart in Devon, which has won several red wine awards. “Quantity wise they were really good. We were cropping at quite good levels and acidity was really low – a good thing for red wines.”

Sharpham grows two red grapes, pinot noir and its cousin, pinot noir précoce, which can be picked earlier, making it perfect for cooler climates. Normally Schwab would subject the grapes to a process to soften their taste. “This year we’re not going to have to do that. Tasting is really brilliant, even in the early wines. We’ll be producing 15,000 to 16,000 bottles of précoce this year and 5,000 bottles of pinot noir compared with just 5,000 in total last year.”

Until now Sharpham’s best red was its cabernet sauvignon merlot from grapes grown in polytunnels. But following this year’s heatwave some of the pinot noir grapes which would normally go into sparkling wine (a mix of chardonnay and pinot) are being diverted to make red wine which will sell for around £16 a bottle.

Facebook Twitter Pinterest Liam Idzikowski harvests his record crop of pinot noir grapes at Lyme Bay winery, Dorset. Photograph: Rene Mansi

Winemakers believe a changing climate is a major factor in the improving quality of the harvest.

“We’re probably one of the only places where it [climate change] is having a positive effect,” Holland said. “Four out of the last six years we’ve harvested in September. Before that it was always in October,” said Holland. “The harvest is getting earlier and we can ripen the grapes to a greater extent. I imagine after this year there will be three, or four, times the amount of still pinot being produced compared with a normal year.”

This is certainly the case at the White Castle Vineyard in Abergavenny, where owner Robb Merchant has just harvested his pinot noir précoce grapes. “It’s the biggest crop we’ve ever had. Probably the best sugar acidity balance we’ve ever had as well,” he said. “Our biggest harvest prior to this was 1,200kg – around 1,000 bottles. This year we’ve done 4.25 tonnes from the same amount of vines.”

Liam Idzikowski, of Lyme Bay winery in Dorset, highlights figures confirming that vineyards in the east of the country have enjoyed more than 1,000 “growing degree” days – a measure of heat accumulation that helps farmers predict crop yields – compared with a 10-year average of 850. Normally the south-west would expect to get around 636 such days. With a couple more weeks still to go, it has already enjoyed 858 this year.

Idzikowski expects 11 tonnes of pinot noir compared with none in 2017 when rain ruined the harvest. “If you set your heart on making pinot noir in England year in year out you are going to have a lot more lows than highs,” he said. “I used to race horses and I was taught to enjoy the winners because there are going to be a lot more losers.It’s like that with pinot noir.”