French wine production for 2021 is expected to plunge 29 percent after unseasonable cold snaps earlier this year wreaked havoc on grape vines, the agriculture ministry said on Tuesday.

Heavy summer rains also fostered mildew growth that took a toll on grapes, with output from the world's largest wine exporter now forecast to be "historically low," the ministry's Agreste statistics agency said.

At 33.3 million hectolitres (880 million gallons), the harvest would be "below the levels of both 1991 and 2017, years that were also impacted by severe spring frosts," Agreste said, adding that it could rival the record lows of 1977.

Nearly all French wine-producing regions, from Bordeaux in the southwest to Champagne in the northeast, were hit by freezing temperatures in early April that came just as buds were burgeoning early after a mild winter.

Chilled wine: the unseasonable cold earlier this year may see output in France test record lows
Chilled wine: the unseasonable cold earlier this year may see output in France test record lows AFP / JEFF PACHOUD

Desperate growers lit fires throughout vineyards in an attempt to raise nighttime temperatures and curtail the losses, while others sprayed vines with water, hoping to form ice "cocoons" on buds that would in fact protect them from freezing.

Agriculture Minister Julien Denormandie has said the frost attack for France was "probably the greatest agricultural catastrophe of the beginning of the 21st century".

Growers of kiwis, apricots, apples and other fruit were also badly hit, along with farmers of other crops such as beet and rapeseed.

World Weather Attribution, an international organisation that analyses the links between extreme weather events and global warming, said in a study in June that a warmer climate had increased the probability of an extreme frost coinciding with a growing period by 60 percent.

France is the world's second-largest wine producer, after Italy.