BERLIN — The tradition has persisted for nearly two centuries in what is now Germany, through wars, epidemics and revolutions. Before dawn on the bitterest of winter mornings, vintners harvest grapes that are frozen on the vine, pressing them before they thaw to produce a small quantity of exquisitely concentrated sweet white wine.

But this winter, for the first time the German wine industry can recall, a cold enough morning came for only one lucky vintner.

“This year will go in down in history,” said Ernst Büscher, a spokesman for the German Wine Institute, a trade group that concluded recently that there would be no 2019 German vintage of the sweet specialty known as ice wine. On Tuesday, it confirmed that one vineyard, Weingut Zimmerle, close to Stuttgart in the country’s south, was lucky enough to have made a small amount, about 100 liters, or 26 gallons.

While that amount is historically tiny, it might be a harbinger of future harvests if weather trends continue.