With the country sweltering in a late heatwave, it is 20C at five in the morning as a harvester crawls along a row of vines, powerful headlights helping guide its way through the darkness.

“Harvesting at night is done for the quality of the grapes, their freshness and taste,” said the driver, Loic Malherbe, who has been at it for three hours already.

“It isn’t bad, it’s just life at a different rhythm… It’s better for the equipment and for people.”

It is already a common practice in several winemaking countries with hot summers but one that is likely to become even more common as climate change accelerates.

Harvesting at night can also help financially strapped growers save money, according to Kees Van Leeuwen, a professor of viniculture at Bordeaux Sciences Agro university.

It means they can skip refrigerating grapes while they are being hauled to be pressed, he explained.

“If harvesting is done at night the temperature of the grapes is lower, especially compared to the very hot days we’ve had this week,” he said.

“There is a huge saving in energy use.”

The harvester dumps the merlot grapes into bins which the vineyard’s owner Stephane Heraud hitches to his tractor to haul to the cooperative.

“It’s been 15 years that we’ve harvested the whites and the rosés at night, and maybe one day we’ll do that for the reds as well,” said Heraud, who also heads the cooperative Vignerons de Tutiac.

“If we harvested at night, we’d have wine that is more oxidised, which in terms of taste is not nearly as nice.”

Heraud climbs up onto his tractor and spreads dry ice (-80C) onto the grapes.

This not only helps keep the grapes cool but reduces the oxygen level in the bins as he drives to the cooperative, which is the largest in one of France’s protected designation regions with 500 growers.

Tutiac has specialised in rosés and accounts for nearly a third of the total produced in the Bordeaux region.

Its pesticide-free rosé caused a stir at a blind tasting conducted by the French wine magazine La Revue des vins de France, being placed fourth among roses from the Provence region which traditionally take top marks in the category.

That night, growers were expected to dump some 500 tonnes of grapes into the various stainless-steel tanks at the wine press, enough to make half a million bottles of wine.

Tutiac’s chief oenologist Paul Oui said consumers like rosés that are light coloured and clear.

To achieve that “you have to limit the transfer of the colour from the skin to the juice and the earlier and cooler we harvest the more we can limit the transfer”, he said.

Night harvesting is already common in Australia and California due to the heat, and the practice is spreading in the Bordeaux region according to Van Leeuwen.

“For whites and rosés, one can imagine that it will become common practice,” said the specialist.

Nor did he exclude that it might one day concern grapes for red wine, which account for 85 percent of Bordeaux’s production.

Rising temperatures make grapes mature faster and push the harvest sooner and into warmer periods, and Heraud confirmed that harvests were indeed happening sooner and sooner.

“I remember when I was small watching my parents harvesting in November,” he said.

“Last year, we were finished on September 30th…,” he added.

“Anyone who says climate change isn’t real isn’t a Bordeaux winemaker.”