VALVIGNERES, France (Reuters) – Scorching temperatures have hurt vines in southern France so much that output will fall but the hot weather could produce a vintage of “exceptional” quality, winemaker Jerome Volle said as he harvested grapes in the early hours of Wednesday to avoid the heat.

A hot spell has hit large parts of France in recent days with temperatures expected to peak at 42 degrees Celsius (107.6 degrees Fahrenheit) in the wine-growing Rhone Valley this week.

“This year we are on a late concentration which will raise the quality of the grapes, and therefore the cost of the wine, as the smoothness and aromas which will emerge will make a rather exceptional wine for the 2023 vintage,” Volle said in his vineyard in Valvigneres in the Ardeche region.

The fall in output was currently expected at between 10% and 20% in the region but with a higher quality, said Volle, who represents Ardeche winemakers.

“The heatwave is not bad if it does not last very long, however it burns the grapes a little so we lose a little production as winegrowers,” he said.

Volle, 49, which uses machines to harvest his grapes, said he had started at 3:00 am.

Authorities advised grape pickers to start and end their work in the morning to avoid extreme heat exposure.

Overnight harvesting also allows to keep grapes cooler, meaning using less energy and avoiding hurting the harvest and aromas, he said.

Jerome Despey, a wine producer of Languedoc wine in southern France and first vice-president of France’s largest farm union FNSEA, told Reuters that the damage caused by the hot weather will lead to lower wine output this year in the south of the country overall.

(Reporting by Clotaire Achi, writing by Sybille de La Hamaide; editing by David Evans)

Red grapes are seen in a truck as a machine harvesting grapes drives through a vineyard during a night harvest in Valvigneres in the Ardeche department, France, August 23, 2023. REUTERS/Clotaire Achi