Snow is expected to fall late morning or early morning, then it is expected to taper off later in the afternoon to freezing drizzle or flurries.
Travel on roads could become hazardous at times.
Five to 10 cm of snowfall or ice pellets is predicted for some areas in Peel and Halton by Monday (Dec. 2) morning.
He said the conditions on the roads are "treacherous", and unnecessary travel should be avoided.
There's a strong chance of freezing rain in the forecast.
The bulk of the precipitation is expected to fall throughout the day on Sunday.
Several millimetres of ice or a few centimetres of ice pellets are possible and the winds are expected to kick up to around 70 km/hr.
The advisory, which was published Sunday (Dec. 1) at 10:12 a.m., said more freezing rain is anticipated before changing to freezing drizzle or flurries in the afternoon. Strong wind gusts up to 60 km/h could produce local blowing snow reducing visibilities.