Environment Canada says Waterloo Region and the Guelph area are expected to get hit with up to 20 centimetres of snow between Monday and Wednesday.
Up to 30 centimetres of accumulation is expected in northern Wellington County.
As of Monday morning, the weather office issued a special weather statement for most of southern Ontario, warning of a “multi-day snowfall event.”
The weather office says rain or snow should begin to fall on Monday morning and then change to snow in the evening.
Guelph and Waterloo Region could see up to 10 cm of snow on the ground by Tuesday morning. Northern Wellington County could see up to 15 cm.
Another 10 cm is possible for the area Tuesday through Wednesday until the low-pressure system moves east by mid-week, said Environment Canada.
Drivers are being warned to prepare for winter driving conditions.