(Bloomberg) - French wine production is forecast to jump 13 percent this year, recovering from the lowest in 40 years as grape harvests rebound in the Burgundy and Beaujolais regions and the Loire River valley.

Output may rise to 46.6 million hectoliters (1.2 billion gallons) from 41.4 million hectoliters in 2012, the Paris-based Agriculture Ministry wrote in an online report today. The outlook is uncertain as vines are still flowering following cold weather, the report showed.

Grapes suffered last year from drought, frost, wetness, disease and hailstorms. The final wine-production figure was more than 10 percent below an initial forecast of 46.7 million hectoliters.

“Due to unfavorable weather conditions for now, flowering hasn’t yet finished in most regions,” the ministry said. “The uncertainty in the first outlook is therefore great. Only after flowering and fruit set can a more precise trend be measured.”

Vines are flowering with a delay of 15 to 20 days in Burgundy and Beaujolais, three weeks in the Jura area, two to three weeks in Bordeaux and about two weeks in the Loire valley, according to the report. France had its coldest spring since 1987, according to weather office Meteo France.

France exported 7.84 billion euros ($10.2 billion) of wine and champagne in 2011, accounting for 14 percent of the country’s farm and food shipments, government data show.