PERINTON, N.Y. (AP) — Colder weather has kicked off the season for a Finger Lakes region specialty: ice wine.

The Rochester Democrat and Chronicle reports (http://on.rocne.ws/W74bV4 ) workers took to the vineyards Wednesday to pick grapes left on the vine to freeze, a process that concentrates their sweetness.

That's the key ingredient for the dessert wine.

Erin Rafalowski, marketing director at Heron Hill Winery on Keuka Lake, tells the newspaper 17 degrees is the perfect temperature to harvest, which usually happens at night.

Heron Hill harvested Riesling grapes and the Casa Larga Winery in Perinton gathered vidal grapes.