As the days get darker and colder, local winemakers are keeping a close eye on the thermostat.
According to Yushi Ren with Summerhill Pyramid Winery, all it takes is one good cold snap and the grapes are prime for ice wine.
"When the temperature drops down below minus eight and above minus twelve for three straight days" said Ren. "By three straight days, all of the water in the grapes is frozen like an ice cube, and when we crush all the grapes we can only get grape juice because the water is iced."
The precise temperatures needed can make it difficult to predict harvest time. He says workers are on call through the winter months to harvest the grapes once the conditions are just right.
"The pick up time normally happens at midnight" said Ren. "All of the grapes, fresh-picked, have to be delivered to the crusher right away."
The frozen grapes produce more concentrated juice, which gives ice wine its sweet flavor.