Update 3:50 p.m.:
The watch has been upgraded to a warning, Environment Canada advised.
Environment Canada has issued a winter storm watch for Greater Sudbury and the surrounding area, with 25-35 cm of snow expected to fall between Tuesday and Wednesday.
Snow will begin during the day Tuesday, as part of the Colorado low crossing Southern Ontario Tuesday and Wednesday.
Strong easterly winds gusting up to 80 km/h are predicted to cause reduced visibility in blowing snow.
Environment Canada says to avoid travel if possible, with rapidly accumulating snow causing potentially hazardous conditions.
"If you must travel, keep others informed of your schedule and destination and carry an emergency kit and mobile phone," said the alert by Environment Canada.
Winter storm watches are issued when multiple types of several winter weather are expected to occur together.