At Herdade da Fonte Santa, a farm in Vimieiro, 150 kms (93 miles) east of the Portuguese capital Lisbon, harvesters start working at midnight in its 20 hectares of vineyards, which are entirely organically farmed in a commitment to sustainability, biodiversity and the future of agriculture.

They work for seven hours under cooler, pleasant conditions, picking grapes beneath the moon and stars to avoid the heat of the day.

The cool night air carries the scent of ripe fruit as workers carefully select each cluster.

Night harvest is a thoughtful and time-honored practice in the world of viticulture, deeply rooted in the desire to preserve the innate freshness and captivating aromas of grapes.

Unlike the more common method of harvesting during the day, night harvest entails picking grapes under the gentle cover of darkness, a decision that transforms not only the fruit but the resulting wines themselves.

At its core, night harvest is a deliberate choice made by winemakers to protect the delicate qualities of their grape crop.

The primary goal is to shield the grapes from the adverse effects of daytime heat, sunlight, and oxidation, all of which can prematurely age the fruit and diminish its aromatic complexity.

By harvesting at night, vintners can lock in the vibrant flavors and fresh bouquet that are the hallmarks of exceptional wine.

Grapes are, by their very nature, incredibly sensitive to temperature fluctuations.

During the day, especially in warmer climates, like in Portugal’s Alentejo province, where this farm is located, the sun can heat vineyard temperatures to well above 40°C (104°F).

This intense warmth accelerates the metabolic processes within grape berries, increasing the rate at which they lose acidity and volatile aromatic compounds.

Additionally, heat can promote the early onset of fermentation, as wild yeasts and bacteria become more active, risking unwanted flavors and spoilage.

At night, however, temperatures typically drop, sometimes by as much as 20°C (36°F) or more.

This cool environment slows the grapes’ metabolism, allowing them to retain their natural acidity, a key contributor to the freshness and balance of the resulting wine.

The preservation of aromatic compounds is equally crucial; these are the delicate molecules responsible for the flowery, fruity, and herbal notes that distinguish great wines from ordinary ones.

Beyond the immediate benefits to grape quality, night harvesting also addresses broader challenges facing winemakers today, particularly those brought on by climate change.

In recent decades, climate change has emerged as a formidable challenge for agriculture worldwide, and the art of winemaking is no exception.

Rising temperatures, unpredictable weather patterns, and shifting seasons have altered the very nature of viticulture.

Amid these changes, winemakers are increasingly turning to innovative practices to preserve grape quality and sustainability.

One such practice—night harvest—has become a powerful tool in adapting to the realities of a warming world.

Climate change is reshaping the timeline and geography of grape cultivation.

“Climate change has greatly influenced our harvest and the process, and we've adapted over the years. Every year, we adapt processes like pruning. We do this later to try to delay the start of the harvest, but even so, we're harvesting earlier every year, so climate change clearly has a significant impact,” says Barbara Monteiro, co-owner and manager at Herdade da Fonte Santa.

Warmer temperatures can accelerate ripening, causing grapes to reach sugar maturity before phenolic and flavor maturity, resulting in wines with higher alcohol content but diminished complexity.

Additionally, extreme heat, drought, and erratic weather events threaten both yield and quality.

As the wine industry grapples with its environmental responsibilities, night harvesting has emerged as a sustainable best practice: lower carbon emissions, reduced need for chemical intervention and water conservation.

AP video by Jorge Jeronimo

Production by Filipe Bento