Their head-mounted flashlights swaying in the darkness, workers at the Bodega Andres Morate vineyards resemble fireflies from a distance as they roll their wheelcarts from one vine to another cutting grape bunches at night.
Forced to start harvesting a few weeks earlier in the season due to brutal summer temperatures and drought influenced by climate change, some Spanish vineyards such as this family business outside Madrid have also switched to nighttime grape picking to avoid working in the sweltering August heat.
Grapes are usually harvested in mid-September, but Andres Morate began this year on 24 August on his 20-hectare plot.
"It's not the usual way... Without the heat we used to harvest later, but harvests have been brought forward in the past few years," he told Reuters.
"And now there is the drought on top of everything... this has been one of the toughest summers ever and each year there are (temperature) records being broken."
Climate change has left parts of the Iberian peninsula at their driest in 1,200 years, according to a study published last month in the Nature Geoscience journal. Spain has suffered three unusually long heatwaves this summer that have stoked devastating wildfires.
Although grapes grew abundantly, the dry heat made them less juicy, Morate said.
Morate, who prides himself on sustainable, eco-friendly production without the use of chemical fertilisers or irrigation, explains that for the best results the grapes need to develop at a gradual pace from when they form on the vine to when they are harvested, but of late, the weather has fast-tracked that process, to detrimental effect.
Working at night, from sundown till 2 or 3 a.m., has its benefits not only for the pickers, but also for the grapes before they are pressed to make wine, he said. The cooler they are when they get to the winery, the more their aroma and flavour is concentrated.
Grape picker Javier, 33, said, "Working at night is much better, it's not too hot, there are no insects, you enjoy working more. During the day we wouldn't be able to be here, we'd just bake."