In the predawn hours of April 27, as temperatures across Bordeaux plunged below freezing, the normally dark and deserted vineyards suddenly sprang to life. Armies of workers decamped into the fields, fires raged and giant fans and helicopter blades whipped up the icy air.

The invading enemy: A frost that threatened one of the world’s most valuable crops, the grapes that produce $4,000 bottles of Chateau Petrus and other prized wines.

The cold, which caused at least $1.1 billion of damage in what France’s winemakers call the biggest disaster in a quarter century, is the latest blow to a French industry that exported 8.25 billion euros worth of wine in 2016 but has lost share globally in recent years. As frost ravaged vineyards from Bordeaux to Burgundy to Champagne, a grower’s fate depended on resources, planning and, not least, luck.

Among the shivering workers in Bordeaux that night was Ines de Bailliencourt of Pomerol estate Chateau Gazin, who quickly realized that she was facing the biggest frost menace to her vines since the great freeze of 1991 that wiped out 90 percent of the vineyard. This time she says the estate was better prepared to ward off the freeze, lighting hundreds of giant, heat-producing candles to warm the vines.

“We were lucky,” said De Bailliencourt, whose family has owned Gazin for the past century and sells its wine for $50 to $100 a bottle. “We lit fires everywhere.”

Less than 6 miles to the south, just below the historic town of Saint-Emilion, others were facing greater losses. Unlike Gazin, on the region’s plateau, Chateau Canon La Gaffeliere sits on low-lying ground and was more vulnerable to pockets of freezing air forming below the slopes. More than 70 percent of its vines were damaged, according to Magali Malet-Serres, who works at the winery.

Some other Bordeaux châteaus say they lost almost everything. Other regions suffered less, but this is the second straight year of deep freezes for Burgundy, where the regional wine board said Friday that 7,400 acres of vineyard were affected.

While climate change has generally led to earlier harvests and riper grapes, cold weather remains an annual threat in France.

This year the risk was acute because an early spring caused vines to bud just as wintry weather returned. Vintners can buy frost insurance, but few do because it’s expensive and of little value for producers because it covers only the value of the grapes lost, not the full amount of the bottled wine. Growers are generally not eligible for disaster relief.

Frost affected as much as 60 percent of the Bordeaux wine-growing areas and will cut volume of the 2017 vintage by as much as 40 percent, according to the Bordeaux wine federation FGVB. That means at least $1.1 billion in lost production from that region alone.

Bordeaux vintners were quick to note that great years like 1945 and 1961 were also hit by frost, with the surviving grapes ripening to perfection. The prospect of tighter supply could fuel demand for the region’s lauded 2016 vintage.

In Champagne, as much as one-quarter of vines owned by the region’s 15,000 growers might be damaged, according to the industry’s trade body in Britain. Because most Champagne is a blend of vintages, houses such as Laurent Perrier and Moet & Chandon can tap into the equivalent of 200 million bottles kept in reserve tanks, along with a further 1.3 billion bottles aging in cellars. While France was most affected, April’s frost damage spread across much of wine-producing Europe, damaging the vineyards that produce riesling in Germany, sparkling wine in southern England and Prosecco in northern Italy.