ON SEPT. 20, pickers for Sonoma’s Kistler Vineyards headed out to chardonnay vineyards at 2 a.m., their headlamps lighting the way. Night harvesting when it’s cool maintains acidity in the grapes, which gives the winery’s cult whites zing and verve. By 9 a.m., grapes were on the crush pad, already being turned into wine.

I thought they tasted delicious. But as in every wine region during the stressful harvest season, the questions are: How big is the crop and how good will the wines be?

“This year we’re lucky in Sonoma,” says Kistler winemaker Jason Kesner, with a relieved grin. “2019 is a classic north California vintage.”

To track the latest about the northern hemisphere’s wine winners and losers in 2019, I’ve been on the ground, phone, twitter, and e-mail. Mother Nature hasn’t been equally generous to every major region this year.

France was particularly hard-hit. Record-breaking heat waves saw sweaty Parisians splashing in the city’s fountains, while high temperatures scorched grapes in vineyards and literally shut down the growing process for a time. Add spring frosts, hail, and wildfires and, according to the France’s agriculture ministry, the country’s overall output is estimated to fall 12%.

As many French winemakers told me: Welcome to the new extremes of climate change. The good news is that they’ve had some practice in years such as 2003 on how to deal with global warming. Despite everything, quality looks very good.

“This is turning out to be a near perfect harvest,” e-mailed Dan Petroski of Larkmead Vineyards in Calistoga. “An excellent vintage that will make wines with great structure.” He wrapped up picking late last week after working 20-hour days. A warm, late summer, followed by a cooling trend and a touch of rain last week, created ideal conditions. Whites are already fermenting, and the cabernet harvest is underway up and down the valley, according to Napa Valley Vintners.

There will be plenty of grapes — probably too many — as both Sonoma and Napa face a grape glut.

Yet the danger of possible power cutoffs could affect how good the wines are. Because downed power lines were blamed for destructive wildfires in 2017 and 2018, utility Pacific Gas and Electric Co. cuts power when fire risk is high. That’s often the case at harvest time, when wineries need electricity to run crushers and temperature-controlled fermentation tanks. For those that lack generators or solar power, an extended outage can bring disaster.

In this normally cool, northeastern region of France, the year’s heat waves were “a trauma for many producers,” according to the well-known Hugel winemaking family. They report yields are down 30% to 40% from last year, especially for gewürztraminer. Happily, the grapes’ concentration from the drought and heat will make wines with serious aging potential. Look for superb rieslings and pinot noirs.

Optimism reigns. White grapes are in and many châteaux will start picking cabernet soon. Despite summer’s heat waves, the general consensus is for high quality and reasonable quantity.

Château Lafite Rothschild’s chief executive officer, Jean-Guillaume Prats, said jokingly in an e-mail, “I know that you should never believe a Bordelais when he tells you this upcoming vintage is the one of the century! But, this year, you should!”

Less mildew is the positive aspect of heat and drought. Last year, biodynamic producer Château Palmer, which doesn’t use preventative chemical sprays, lost most of its grapes in Margaux to a virulent outbreak after a warm, humid spring. No problems this year. Says CEO Thomas Duroux: “We finished picking merlot last week, and aromas are fresh and floral, with unusually good balance that pleases me a lot.”

“2019 is ‘the perfect storm’ of a vintage,” said Laurent Drouhin of top négociant house Drouhin, which owns vineyards in many parts of Burgundy. “We keep smiling because some wines will be great.” The mix included the hottest temperatures since the time of the Black Death 700 years ago (!), frost in April, rain in June, and no rain for nearly four months.

Drouhin’s harvest started on time on Sept. 13, and Laurent’s winemaking brother Frederic reports, “The first reds show an intense and beautiful color, good concentration, great balance and acidity and depth. The whites also show good richness with balance.” It’s a great year for reds, with slightly higher alcohol than usual.

The downside is very low yields. In just one April night, frost destroyed about 30% of the crop in Macon, though what’s left is making wines with good acidity and aromas.

Export company Le Serbet gathered reports from 65 producers in its portfolio, and head of marketing Peter Wasserman says the loss of grapes varies from vineyard to vineyard; in some places it may be as much as 50% to 60% lower than normal. Northern appellations such as Gevrey-Chambertin seem to have done best, down only 10%.

With less wine, you might predict even higher prices, but producers worry that this would drive away consumers.

Harvest started in early September and is now finished. The year has been far more challenging than was 2018, a great vintage — and a big one.

As Sebastien Legolvet, cellar master at Champagne Henri Giraud points out, in 2019, the usually cool region had the wettest winter ever recorded, followed by an incredibly dry summer whose temperatures hit an unheard-of 43° Celsius (109° Fahrenheit). About 1,000 hectares were wiped out by frost, some areas suffered hail, and many domaines were hard-hit by mildew, requiring serious sorting in the vineyard. Yields are down about 17%.

Top Champagne house Bollinger lost around 11% of the crop, said chef de caves Giles Descotes, adding, “But we are more than confident for the quality of the pinot noir, which has strong acidity and beautiful aromas of fruit.”

Vitalie Taittinger, whose family owns Taittinger, extolls the “aromatic richness” of this year’s grapes.

The weather tale here is much the same as elsewhere in France. Quantities range widely, from catastrophic to just all right, according to star winemaker Jacky Blot of Domaine de la Taille Aux Loup. The young vines in Vouvray, he says, are in bad shape.

Appellations Anjou, Savennieres, and Bourgueil look much luckier. The good news is that the grapes that survived have excellent acidity and gorgeous aromas.

Last year, harvest was a week to 10 days early; the 2019 start date is back to normal, with reds being picked last week. A mild winter helped kickstart the vines, cool April and May slowed down growth, and then came heat and some sunburned grapes.

Benjamin Gras at Domaine Santa Duc in Châteauneuf-du-Pape says old vines weathered the drought best because of their deep roots, and he was surprised by the acidity in the grapes, despite the drought. Grapes have complexity, but lack of rain means there’s not much juice, with yields down 20%.

The Perrin Family, which owns Château de Beaucastel and several other organically farmed wineries in the southern Rhône, e-mailed: “We’re very confident for a great vintage if the harvest finishes as it has started.” That, of course, is always a big if.

In the Languedoc, Gérard Bertrand, one of the region’s pioneers, with 15 estates, says 2019 is a great vintage. He’s convinced that using biodynamic practices helped the vines adapt to drought, which didn’t affect the volume of grapes.

Don’t worry about next year’s Provence rosés; there will be enough for us all. Bertrand Leon, technical director for Château d’Esclans, makers of the ubiquitous Whispering Angel, e-mailed, “We anticipate the 2019 vintage to be great, aromatic and fresh with good acidity.” Hot summer days, cool nights, and rain at the right time kept quality high.

This will be the first harvest for a new terroir designation, Côtes de Provence Notre-Dame des Anges, just recognized in August.

Regional consorzi are predicting a good year with yields reduced about 10% to 15%. (That’s only partly because of weather; Chianti is reducing production because its wine sales are down in the US and Germany, its two biggest markets.)

Many areas suffered yet another cold, rainy spring, which waterlogged the soil and delayed the growing cycle by about two weeks.

Still, quality seems to be good in Tuscany. Stefano Cinelli Colombini at Fattoria dei Barbi in Montalcino says the rains at the beginning of September were the final refreshment the grapes needed. “They’re rich in flavor,” he wrote. “We’re expecting Brunellos with high alcohol, powerful wines that will have extreme aging potential.”

Last year Mother Nature smiled on England, a beneficiary of global warming. In 2018, some winemakers literally didn’t have enough fermentation tanks for the bumper crop of grapes. This year, there won’t be a grape bonanza, as 2019 appears more typical. All signs are positive, says the head winemaker at top sparkling-wine producer Nyetimber, which is launching this year in the US Fingers are crossed. The winery started picking last week — amid the threat of rain.

At press time, the jury is still out on Spain’s 2019 harvest. Winter was mild and very dry, with more spring rain than usual, and despite the high temperatures elsewhere in Europe, the summer was not too hot, says Victor Urrutia, chief executive officer of CVNE in Rioja, which also owns vineyards in Ribera del Duero and Galicia.

He thinks this harvest will be very good to excellent but — as elsewhere in Europe — with much lower yields than expected. — Elin McCoy, Bloomberg