BISMARCK, N.D. — North Dakota’s wine industry has seen an unusually productive harvest despite severe drought conditions this summer.

Grapes grown in the state are cold-climate varieties, but heat allows the grapes to ripen faster, The Bismarck Tribune reported. The state’s grapes are usually more acidic, but as the grapes ripened this year, the acid dropped and they became sweeter.

“It was actually a great year for grapes,” said Deb Kinzel, of Dickinson-based Fluffy Fields Vineyard & Winery.

Grapes that are used to create wine need to reach a certain sweetness and sugar level called brix, according to Randy Albrecht, operator of Wolf Creek Winery in Coleharbor. A brix level of 22.5 will make a wine about 12 percent alcohol.

“We generally saw higher brix and lower acid, which makes winemakers smile,” Albrecht said.

“A brix of 22 to 24 is really where we like to see the grapes,” he noted. “If we harvest with less, it produces less alcohol and it’s more acidic.”

The state’s wine industry has been successful and is expected to continue its rapid growth.

The industry expects the industry to grow at a rate of about 200 percent annually through 2020, said RayAnn Kilen, a consultant for the industry. That’s causing some concern that there isn’t enough fruit being commercially grown to meet demands in the future.

Wine makers currently purchase nearly 80 percent of their produce from out of state.