Winemakers in Southern Europe Grapple With Extreme Weather

“Weather is changing and it’s changing a lot,” said Mr. Salamini, 47 years old. This year, his Luretta winery is set to start harvesting on Aug. 16, a month earlier than what was normal a generation ago.

Grape vines are usually able to adapt to hot, dry climates but conditions across Southern Europe have become so extreme this summer that many winemakers worry yields will fall and that the quality of their wine could suffer.

Analysts say that lower yields could prompt some producers to raise prices, though they will likely be wary to do so at a time when some consumers are tightening their belts amid rising inflation.

While there is still time for vines to improve in some regions, vineyards spanning Italy, France and Spain—the world’s three largest wine producers—say they need to adapt to rapidly changing climates.

Several record-breaking heat waves and drought have already hurt various European crops in recent months. Some parts of Portugal, Spain and Italy broke 100 degrees Fahrenheit several times throughout the summer. Officials in France have declared this year’s drought the worst ever on record and placed restrictions on water use. Some regions in Spain did the same, as reservoir levels declined to historic lows.

While forecasts can still change, the best-case scenario for wine production in Spain this year is a decline of 5% to 10% on last year’s historic low, according to Jose Saiz, a wine market analyst at Mintec, a data provider. If the drought continues, parts of Spain could see a 25% reduction, he said.

French officials said earlier this month that while they expect wine production to rebound this year from last year’s numbers, which were also historically low because of frost, drought threatened to limit the recovery.

Vineyard owners in central and northern Italy say their vines are hurting but that they can’t be certain if it will be a good or bad year until harvest begins in mid-August. It will continue through September.

Axel Heinz, estate director of Italy’s Ornellaia vineyards, said every year since 2017 has brought unpredictable conditions, though most vintages had ended up turning out well in different ways. Still, while he had been pleasantly surprised by the wines, he said changing weather “means that we’ll be in a state of uncertainty until the end of our careers.”

Alberto Coffele said he hoped that recent rainfall and a drop in temperatures could be enough to recover the harvest at his vineyard in the Veneto region of northern Italy.

But until recently, his grapes weren’t swelling and some leaves had started to turn yellow and fall, he said, blaming “the strong and persistent stress suffered.”

“The physiology of the plant is basically blocked,” Mr. Coffele added.

When vines endure extreme conditions, they do everything they can to survive, sucking up any water they can. That, though, means less water gets to the grapes, sometimes leading to smaller berries and possibly lower yields.

At Michel Gassier’s two family-operated wineries in France’s Rhone Valley, the latest ripeness checks found berries at the smallest since records started 30 years ago. In some batches, the berries and vines are burned up.

Other vineyards nearby that don’t have as much irrigation set up are in even worse condition.

“It would look like you took a blowtorch and you went on the leaves and you just burned them,” Mr. Gassier said.

Mr. Gassier attributes weather changes in recent years to climate change. “Unfortunately, the change is so rapid that even nature has a hard time adapting to the drastic conditions that we have,” he said.

In Spain, Miguel A. Torres said he expects his Familia Torres winery to harvest 20% to 30% less grapes this year.

This summer’s weather conditions are “the worst I’ve seen in more than 50 years in the business,” he said.

His winery is based near Barcelona in the Penedès region, which Mr. Torres said had seen no rain over the past three months. While he was able to irrigate 40% of his highest-quality grape vines, the rest are suffering. He plans to harvest the majority earlier than expected.

Early harvests can be good for certain types of wines that require slightly less ripened grapes, like sparkling wines, but for many others, early harvests aren’t always ideal.

Smaller, heat-stressed berries not only often lead to less wine but can also impact the balance of acidity and sugars, which is important for taste. Higher temperatures and earlier ripening cause berries to have a different balance.

A continuing lab study of Languedoc-Roussillon red wines from the south of France found that acidity has been declining since the 1980s, and alcohol content rising, as conditions get hotter.

The changing profile poses a challenge for parts of Europe that have cultivated specific types of wines for centuries.

Lucio Salamini’s vineyard has suffered from a lack of rainfall that has left water levels abnormally low at the nearby Lake Trebecco. Francesca Volpi for The Wall Street Journal

“When [consumers] buy from Bordeaux, or they buy from Burgundy, there is a certain expectation as to how it should taste and what it should be,” said Dr. Glen Creasy, a viticulturist with Terre des 2 Sources, a vineyard in the south of France. “There’s a qualitative aspect of the wine that is supposed to be associated with a region and that is absolutely changing.”

In response, some vineyards say they are working to improve soil conditions to retain water, seeking out new rootstock less susceptible to extreme heat and setting up irrigation systems. However, irrigation systems are strictly regulated and sometimes restricted in parts of Italy, Spain and France because of traditional standards set by local governing bodies.

Back in Italy, Mr. Salamini said he just needs time to adapt to the changing climate.

“The problem is not that it’s impossible to make wine,” he said. “The problem is that we need to change the way of cultivating our vineyards.”

Write to Sara Ruberg at sara.ruberg@wsj.com