Jefferson, St. Lawrence and Lewis counties have been placed under a winter storm watch from today through late Wednesday, according to the National Weather Service.
Forecasts call for heavy snow, possibly mixed with sleet and freezing rain. Possible accumulations of 6 inches or more could make travel difficult.
The advisory said light snow will begin today, but could change to a mix of snow, sleet and freezing rain by Wednesday morning.
Colder air is expected to settle back over the region by Wednesday afternoon, and Wednesday night presents the highest likelihood of significant snow accumulation.
Snow-covered roads and reduced visibility could disrupt early holiday travel through Wednesday night, the weather service advisory said.